Post by andrew on Jan 25, 2020 20:43:58 GMT -5
Hello Carl, thank you for writing this article it was really helpful when trying to understand ORP and its application is aquarium husbandry. I have a few questions about your article and some others I have about another article I read regarding ORP in anaerobic wetland soils that you can probably answer. I have attached it if you would like to look at it. My goal in reading about soil fertility and how different aspects of soil fertility apply to a planted tanks with a soil substrate. I am trying to learn about planted tanks with a soil substrate and what is happening in successful aquariums vs. tanks where there seems to be one problem after another. I have heard it all on forums from never ending cycling, high NH3 and NO3 levels for long periods of time sometimes killing plants and animals, root rot, nutrient decencies, if not animal death sever unexplained infections in fish and certain death in inverts. Plants that melt even when parameters are in line. There are so many problems that can occur if you don't at the very least lime your soil to provided pH buffering capacity to your amended soil. And add some type of fertilizer that will cover your micros as NPK and Sulfur are provided by the decomposition of organic matter in amounts sufficient to grow a lot of plants in the aquarium hobby and Ca and Mg are provided by the dolomite lime. I also think that me soaking my organic matter the first time in chlorine and chloramine free water for a month helped reduce NH3 and NO3 swings in the tank once setup because the different bacterias had a chance to reproduce in anaerobic soil conditions where no animals or plants can be harmed by fluctuating N levels, the nitrogen cycle can do it's thing, excess N can be reduced to N2 and leave the water column via gas exchange slowly or not it doesn't matter.
I have read an article in 2hr Aquarist about substrates or rather what the writer regards as the best substrates, soils. It talked about pore spacing/soil structure, organic content, cation exchange capacity (CEC), nutrient levels, and pH. All of them I have a descent understanding of. However, I recently learned about redox of soils and waters in wetlands. I started googling "aquarium redox potential" and found your article.
A few years ago I had an planted tank with soil substrate about 3" deep for about 3 years and it grew some Amazon Swords and Jungle Val well. I bred swordtails almost the entire time and never had any problems with fish health. I fed like crazy and rarely did water changes (once a month). I used mineralized top soil, red sandstone sand, crushed coral, mineral mud, and an eco complete cap. My. thinking was that I could add some important nutrients to the soil with additions of different sediments, sands, and a planted tank substrate touted for continuously supplying micronutrients. I didn't consider the properties of substrates I mentioned earlier. I didn't really know what I was doing. I read what I could find on forums which didn't have very much info. So I did what made sense to me and disregarded almost everything said to be avoided when using soil. I read tons of posts and most of what I could dig up were opinions and a lot of people that in my opinion didn't or weren't having success with soil. There were a few that had very good results but all of them dosed fertilizers, most injected CO2, and their soil had few soil components. I found some people that used different types of baked clays like SafeTSorb or cat litter with either mineralized topsoil or unmineralized top soil. The nicest tank I saw used a 2" substrate depth consisting of MTS, peat moss, and cat litter (soaked in lime for some reason), Osmocote Plus in DIY root tabs, and excel. A simple recipe that did not consider many things pertaining to soil fertility nor did it include a source of all of the essential macro, micro nutrients, and trace elements.
I want to use soil because I have read that it is an ideal substrate for aquatic plants and it makes sense when you consider ORP and CEC in soil consisting of organic matter in various stages of decay and sediments with many different minerals or cations. Soil is supposed to be a source of all essential nutrients for aquatic plants. Yes they can absorb nutrients from the water but not all are available in water even when a complete soil substrate is provided. I have read that aquatic plants with roots have roots that are specifically for excoriating nutrients from the soil because they need them to get everything they need without deficiencies arising. The reason they need them is because not all nutrients are available in the water column or are not present in sufficient amounts. It has also been said by some advanced aquarists that aquatic plants prefer to have fairly large amounts of nutrients available in the soil because it is easier for them to use.
Furthermore, soil organic matter consisting of non-humic organic molecules released directly from cells of fresh residues, such as proteins, amino acids, sugars, and starches. This part of soil organic matter is the active, or easily decomposed fraction. The activity in these soils refers to microbial processes essential in nutrient cycling and the bacteria living in these soils help balance a soil tank as it matures helping to reduce organics from fish waste naturally without gravel vacuuming or frequent water changes. These soils will be rich in bacteria where packaged planted tank substrates are empty they have no organics to be reduced and used as food for microbes.
My improved recipe is:
Organic Matter: %50 by volume. In three equal parts.
*Peat moss humus (very decomposed so it will not leach nitrate and other nitrogen compounds into the water as it decomposes, high CEC, and low pH to help naturally weather the sediments I want to add).
*Worm Castings (for pH buffering, slight amounts of NPK, micros, trace minerals, plant enzymes, and bacteria)
*Compost (for organic matter that will break down to feed soil microbes and produce CO2, NH4, NH3, N03, and sulfur. Also a great medium for various types of soil bacteria.)
Organic matter and the microbes that live within it are supposed to be very helpful in maintaining a healthy balanced aquarium. Now that I have a little understanding of ORP this makes more sense.
Sediments: 50% by volume.
*Greendsand (potassium, iron, micros, trace minerals, aid in correct soil structure helping breakup organic matter and clays)
*Dolomite lime (calcium, magnesium, to buffer for organic matter to desired pH)
*Azomite (trace minerals and soil structure)
*Basalt Grit (calcium, iron, magnesium, manganese, and soil structure).
*Soft Rock Phosphate (source of Phosphorus and soil structure)
*Montmorillonite Clay (minerals, soil structure, and it is supposed to help keep pond and aquarium fish and inverts healthy when dissolved in water probably because of its effects one ORP, flocculation) Chemically, it is hydrated sodium calcium aluminium magnesium silicate hydroxide (Na,Ca)0.33(Al,Mg)2(Si4O10)(OH)2·nH2O. Potassium, iron, and other cations are common substitutes, and the exact ratio of cations varies with source.
*Lava Rock Pumice (for soil structure that does not lead to soil compaction over time, media for bacteria colonization, and its micropores allow O2 diffusion into the lower parts of the substrate preventing overly anaerobic conditions).
Soil prep steps:
1) I plan on adjusting the pH of the organic matter with dolomite lime to about 7.0. I will do this over a period of a month while submerging the organic matter and letting the soil CEC absorb the Ca and Mg until it is saturated and cannot hold anymore Ca or Mg. This will also give time for ORP of the soil to stabilize, I think. Retesting the KH, GH, pH, and TDS every few days to get an idea of how the buffers are holding up and to see if GH and TDS drop when Ca and Mg are being absorbed out of the water into the soil through CEC reactions. When the organic matter is stabilized at around my target pH 7.0, I am done with the lime and should have sufficient Ca and Mg for redox balance it the soil water solution for the next few weeks, at least, until the weathering of the sediments bring Ca, Mg, and other cations back up in the soil and water. I also want to use wonder shells and Montmorillonite Clay or some sort of GH booster.
2) Add the mineral components of the mixture until I have approximately 50/50, organic matter/mineral sediments. I want greensand to make up 20% of sediment volume, Azomite 5% of sediment volume, Basalt Grit 20% of sediment volume, Soft Rock Phosphate 5% of sediment volume, Montmorillonite Clay 20% of the sediment volume, and lava rock pumice 30% of sediment volume. These sediments may increase pH over my target of 7.0. I think all I would have to do is wait if that happens for the peat to reduce the KH and pH of the water followed by reduction of the pH of the soil to a more stable value, with that added basic cations produced by weathering of the mineral rich sediments.
3) 3" deep soil depth covered with a 1/2" of black diamond blasting sand.
I am aiming for a slow release source of Potassium, Calcium, and Magnesium as well as all of the trace elements. I am shooting for this substrate to last at least 2 years. This is about how long carbon, NPK, and sulfur will take to be depleted. Meaning I want to only add mineral supplements, wonder shell, montmorillonite clay, or GH booster to maintain redox potential and balance. I do not want to fertilize regularly other than reductive mineral supplementation for a desirable ORP. I want to rely on the organic matter to provide the essential nutrients, nitrogen (NH4, NH3, and NO3) and SO4 or S from decomposition of soil organic matter and the rest of the nutreints will come from the sediments. Time and acidic soil pH due to carbonic acid forming reactions of CO2 and water in organic matter will chemically weather the sediments and release essential cations and trace minerals.
I think if I tune in my understanding of ORP and how all of this could work together I might have something.
I have a background in organic gardening and use these amendments in soil I grow gardens in. I am confident they will work but not sure how to use them and application rates in the aquarium environment, because I have not found anyone that has done soil like this. Why wouldn't one create a more natural soil environment that considers all that we know about soil fertility. Why would someone not build a planted tank soil capable of providing all essential nutrients to the plants over time instead of a clay or mineral rock substrates that need frequent fertilization. Furthermore, now that I have read your article and learned how important all cations are to the redox balance of the aquarium water and soil. I am even more confident that mixing organic matter and various sediments, volcanic ashes, and clays is not only possible, but, promising.
My questions start with achieving balance in a environment where there will be organic matter decomposing and chemical sediment weathering. I assume that there will be a fluctuating soil ORP as a result of the oxidizing organic matter and the high amounts of reducing cations in the soil. As these cations move from site to site with high affinity cations pushing low affinity cations into the soil solution and into new cation exchange sites ORP of the soil will stabilize at some point and then I can make adjustments with the addition of more cations particularly Ca, Mg, and K. Is this correct?
Do you think I should shoot for a specific ORP in the soil before I use it in the aquarium?
Should I buy a ORP meter to test the soil before using it as a substrate in the aquarium?
Would I need a different ORP meter for water and soil?
How do you think the Redox Balance will play out in a soil with these mineral amendments and different organic matter in various stages of decomposition?
Do you think the mineral rich sediments could increase ORP to unsafe levels and cause unhealthy fluctuations or imbalances with a large amount of organic matter present?
Are my questions that aren't considering an unknown rate of organic matter reduction, unknown rate of sediment weathering, or unknown sediment cation make up, difficult to answer?
I know I cannot expect these sediments to weather and mineralize the soil and water at a constant rate or one that is predictable in anyway. I would also have to assume the minerals produced by the weathered sediments were of the appropriate make up and proportions to balance redox in the water and soil. I am thinking I should follow the recipe I have and see what happens over time testing NH3, NO3, NO2, TDS, KH, GH, pH, and Redox Potential as the soil and water age. Not that I don't think this will eventually work out but to understand how these variables are being effected as this idea becomes a reality. While keeping an eye out for nutrient deficiencies, root rot as time passes, or anything else that effects life inside the aquarium.
Because of the heavily oxidizing environment of decomposing organic matter. I will use wonder shells, GH booster or Montmorillonite Clay if need to raise ORP, keeping gas exchange rates and O2 levels as high as possible, using a UV sterilizer, high intensity lighting, heavy planting of fast growing plants from the beginning, and aggressive pruning to reduce the need for water changes to once a month or less are all things I will do. It will either work like expected or not. I will be able to keep ORP in an acceptable range or I won't and then I will have to use other tactics to raise ORP. I am confident that I will be able to grow rooting plants very well after the soil is built. Given time to reach equilibrium, and nutrient cycling, nitrifying, denitrifying, and carbon oxidizing bacteria are given time and appropriate conditions to multiply the soil will be ready to plant in.
Now what is an acceptable redox potential for aquatic plants is very different from what is acceptable for healthy redox potential in water for fish. Specifically for me, guppies that like higher concentration of Ca and Mg as well as above average GH leading me to think they like a higher water ORP as well. I have read that redox potentials for waterlogged soils is usually very low as well as pH, due to the lack of cations and O2 found in these soils. I may be able to have a soil substrate with a higher ORP due to the addition of Mg and Ca from the lime and allowing it time to find an target ORP and pH range in which it fluctuates. The high CEC of the soil will allow large amounts of Ca and Mg access to the exchange sites where they can bond and buffer soil pH. The high CEC allows for more of these cations to bond and thus it takes significantly more Ca and Mg to buffer pH of high CEC soils which are usually on the acidic side as well. This means I will have a lot of exchangeable Ca and Mg for plants and animals to use when I start adding other cations to the mixture which will exchange places with this Ca and Mg making them available to plants and animals in the aquarium water as they are replaced by cations with higher binding affinity to CEC substrates. These sediments will slowly release exchangeable cations through chemical weathering caused by acidic environments in the soil and bacterial acidification of anaerobic soils in the soil organic matter, namely the peat moss. This should help replenish Ca and Mg in the soil and water then available for plants and animals inside the aquarium.
I though a long time about nutrient ratios recommended for aquatic plants and decided that it would be impossible to get exact ratios because these mineral sediments don't have a definite mineral content. Only minerals known to be in them noting definite with percentages. So I went with someone else's idea that plant do need specific ratios of nutrients the just need adequate levels of essential nutrients. Having none of the macronutrients being a limitation for growth. The thing with ratios is that some plants will luxury feed on certain nutrients if they are available to access them and this will throw nutrient ratios in the plant matter out of balance leading to what would look like deficiencies due to an over absorption of the nutrient that was over consumed. The limiting nutrient should be carbon but I don't think it will be as low as non soil tank with low amounts of carbon oxidizing bacteria in the carbon rich compost where CO2 is naturally produced. I have read that natural waters supportive of plant growth have levels closer to 10-30ppm due to organic matter present in soil and soil organic carbon being converted to CO2 in many microbial processes. Because this soil is fairly heavy in inorganic matter that is decomposing. I am going to shoot for a soil redox potential around +250 mV and a pH around 7.0. With my water redox potential target around the same and the soil with a slightly higher pH around 8.0 and hardness around 11dGH appropriate for guppies. I might use crushed coral in my canister filter to boost water pH and GH to desired levels if the wonder shell won't do it. Crushed coral will also provide Ca and Mg to keep ORP from going low due to Ca and Mg being used my the plants and fish in the tank.
I am having a hard time trying to understand my research on ORP in soil and water and how it behaves differently in waterlogged soils.
I think the soil and water will both effect each other, right? The ORP will be highest in the water column where O2 is present with high mineral content. Then over time ORP of soil will start to decrease as O2 at the surface layer of the substrate is reduced my bacteria. If I understand correctly as soil depth increases ORP, pH, and dissolved O2 will decrease.
I have found in the attached article (link is at bottom of post) this information: "By-products of aerobic respiration are soluble organic compounds, carbon dioxide, ammonia, nitrite, nitrogen gases, ferrous iron, manganous manganese, hydrogen sulfide, hydrogen, and methane. These substances are transported within the soil profile and into water above through soil diffusion, seepage, and sediment disturbances."
Some of these substances are oxidants others are reductants, right?
Do you have any idea how all of this might come together to create an ORP in the water column when using a mineral and organic matter rich substrate?
Does it come down to the total amount of oxidizers and reducers in the water column and/or soil which are hard to quantify?
Do you see anything I don't understand about my recipe or any oversights I have made applying the ingredients in the steps I have?
Will the pH buffering with dolomite lime work the way I think?
Will these Ca and Mg cations be made available for use by plants in the soil or for animals in the water when various cations are introduced to the soil through chemical weathering of the mineral sediments, pushing the Ca and Mg off CEC sites and into soil solution or the water column?
Cations in aquariums move through the soil solution up into the water column and possibly back into the soil, repeating this over and over again until the cations are needed by a plant of animal?
Thank you for you time! I hope you have a minute to answer what you can.
283.Anaerobic Soils. In Encyclopedia of Soi....pdf (466.59 KB)
I have read an article in 2hr Aquarist about substrates or rather what the writer regards as the best substrates, soils. It talked about pore spacing/soil structure, organic content, cation exchange capacity (CEC), nutrient levels, and pH. All of them I have a descent understanding of. However, I recently learned about redox of soils and waters in wetlands. I started googling "aquarium redox potential" and found your article.
A few years ago I had an planted tank with soil substrate about 3" deep for about 3 years and it grew some Amazon Swords and Jungle Val well. I bred swordtails almost the entire time and never had any problems with fish health. I fed like crazy and rarely did water changes (once a month). I used mineralized top soil, red sandstone sand, crushed coral, mineral mud, and an eco complete cap. My. thinking was that I could add some important nutrients to the soil with additions of different sediments, sands, and a planted tank substrate touted for continuously supplying micronutrients. I didn't consider the properties of substrates I mentioned earlier. I didn't really know what I was doing. I read what I could find on forums which didn't have very much info. So I did what made sense to me and disregarded almost everything said to be avoided when using soil. I read tons of posts and most of what I could dig up were opinions and a lot of people that in my opinion didn't or weren't having success with soil. There were a few that had very good results but all of them dosed fertilizers, most injected CO2, and their soil had few soil components. I found some people that used different types of baked clays like SafeTSorb or cat litter with either mineralized topsoil or unmineralized top soil. The nicest tank I saw used a 2" substrate depth consisting of MTS, peat moss, and cat litter (soaked in lime for some reason), Osmocote Plus in DIY root tabs, and excel. A simple recipe that did not consider many things pertaining to soil fertility nor did it include a source of all of the essential macro, micro nutrients, and trace elements.
I want to use soil because I have read that it is an ideal substrate for aquatic plants and it makes sense when you consider ORP and CEC in soil consisting of organic matter in various stages of decay and sediments with many different minerals or cations. Soil is supposed to be a source of all essential nutrients for aquatic plants. Yes they can absorb nutrients from the water but not all are available in water even when a complete soil substrate is provided. I have read that aquatic plants with roots have roots that are specifically for excoriating nutrients from the soil because they need them to get everything they need without deficiencies arising. The reason they need them is because not all nutrients are available in the water column or are not present in sufficient amounts. It has also been said by some advanced aquarists that aquatic plants prefer to have fairly large amounts of nutrients available in the soil because it is easier for them to use.
Furthermore, soil organic matter consisting of non-humic organic molecules released directly from cells of fresh residues, such as proteins, amino acids, sugars, and starches. This part of soil organic matter is the active, or easily decomposed fraction. The activity in these soils refers to microbial processes essential in nutrient cycling and the bacteria living in these soils help balance a soil tank as it matures helping to reduce organics from fish waste naturally without gravel vacuuming or frequent water changes. These soils will be rich in bacteria where packaged planted tank substrates are empty they have no organics to be reduced and used as food for microbes.
My improved recipe is:
Organic Matter: %50 by volume. In three equal parts.
*Peat moss humus (very decomposed so it will not leach nitrate and other nitrogen compounds into the water as it decomposes, high CEC, and low pH to help naturally weather the sediments I want to add).
*Worm Castings (for pH buffering, slight amounts of NPK, micros, trace minerals, plant enzymes, and bacteria)
*Compost (for organic matter that will break down to feed soil microbes and produce CO2, NH4, NH3, N03, and sulfur. Also a great medium for various types of soil bacteria.)
Organic matter and the microbes that live within it are supposed to be very helpful in maintaining a healthy balanced aquarium. Now that I have a little understanding of ORP this makes more sense.
Sediments: 50% by volume.
*Greendsand (potassium, iron, micros, trace minerals, aid in correct soil structure helping breakup organic matter and clays)
*Dolomite lime (calcium, magnesium, to buffer for organic matter to desired pH)
*Azomite (trace minerals and soil structure)
*Basalt Grit (calcium, iron, magnesium, manganese, and soil structure).
*Soft Rock Phosphate (source of Phosphorus and soil structure)
*Montmorillonite Clay (minerals, soil structure, and it is supposed to help keep pond and aquarium fish and inverts healthy when dissolved in water probably because of its effects one ORP, flocculation) Chemically, it is hydrated sodium calcium aluminium magnesium silicate hydroxide (Na,Ca)0.33(Al,Mg)2(Si4O10)(OH)2·nH2O. Potassium, iron, and other cations are common substitutes, and the exact ratio of cations varies with source.
*Lava Rock Pumice (for soil structure that does not lead to soil compaction over time, media for bacteria colonization, and its micropores allow O2 diffusion into the lower parts of the substrate preventing overly anaerobic conditions).
Soil prep steps:
1) I plan on adjusting the pH of the organic matter with dolomite lime to about 7.0. I will do this over a period of a month while submerging the organic matter and letting the soil CEC absorb the Ca and Mg until it is saturated and cannot hold anymore Ca or Mg. This will also give time for ORP of the soil to stabilize, I think. Retesting the KH, GH, pH, and TDS every few days to get an idea of how the buffers are holding up and to see if GH and TDS drop when Ca and Mg are being absorbed out of the water into the soil through CEC reactions. When the organic matter is stabilized at around my target pH 7.0, I am done with the lime and should have sufficient Ca and Mg for redox balance it the soil water solution for the next few weeks, at least, until the weathering of the sediments bring Ca, Mg, and other cations back up in the soil and water. I also want to use wonder shells and Montmorillonite Clay or some sort of GH booster.
2) Add the mineral components of the mixture until I have approximately 50/50, organic matter/mineral sediments. I want greensand to make up 20% of sediment volume, Azomite 5% of sediment volume, Basalt Grit 20% of sediment volume, Soft Rock Phosphate 5% of sediment volume, Montmorillonite Clay 20% of the sediment volume, and lava rock pumice 30% of sediment volume. These sediments may increase pH over my target of 7.0. I think all I would have to do is wait if that happens for the peat to reduce the KH and pH of the water followed by reduction of the pH of the soil to a more stable value, with that added basic cations produced by weathering of the mineral rich sediments.
3) 3" deep soil depth covered with a 1/2" of black diamond blasting sand.
I am aiming for a slow release source of Potassium, Calcium, and Magnesium as well as all of the trace elements. I am shooting for this substrate to last at least 2 years. This is about how long carbon, NPK, and sulfur will take to be depleted. Meaning I want to only add mineral supplements, wonder shell, montmorillonite clay, or GH booster to maintain redox potential and balance. I do not want to fertilize regularly other than reductive mineral supplementation for a desirable ORP. I want to rely on the organic matter to provide the essential nutrients, nitrogen (NH4, NH3, and NO3) and SO4 or S from decomposition of soil organic matter and the rest of the nutreints will come from the sediments. Time and acidic soil pH due to carbonic acid forming reactions of CO2 and water in organic matter will chemically weather the sediments and release essential cations and trace minerals.
I think if I tune in my understanding of ORP and how all of this could work together I might have something.
I have a background in organic gardening and use these amendments in soil I grow gardens in. I am confident they will work but not sure how to use them and application rates in the aquarium environment, because I have not found anyone that has done soil like this. Why wouldn't one create a more natural soil environment that considers all that we know about soil fertility. Why would someone not build a planted tank soil capable of providing all essential nutrients to the plants over time instead of a clay or mineral rock substrates that need frequent fertilization. Furthermore, now that I have read your article and learned how important all cations are to the redox balance of the aquarium water and soil. I am even more confident that mixing organic matter and various sediments, volcanic ashes, and clays is not only possible, but, promising.
My questions start with achieving balance in a environment where there will be organic matter decomposing and chemical sediment weathering. I assume that there will be a fluctuating soil ORP as a result of the oxidizing organic matter and the high amounts of reducing cations in the soil. As these cations move from site to site with high affinity cations pushing low affinity cations into the soil solution and into new cation exchange sites ORP of the soil will stabilize at some point and then I can make adjustments with the addition of more cations particularly Ca, Mg, and K. Is this correct?
Do you think I should shoot for a specific ORP in the soil before I use it in the aquarium?
Should I buy a ORP meter to test the soil before using it as a substrate in the aquarium?
Would I need a different ORP meter for water and soil?
How do you think the Redox Balance will play out in a soil with these mineral amendments and different organic matter in various stages of decomposition?
Do you think the mineral rich sediments could increase ORP to unsafe levels and cause unhealthy fluctuations or imbalances with a large amount of organic matter present?
Are my questions that aren't considering an unknown rate of organic matter reduction, unknown rate of sediment weathering, or unknown sediment cation make up, difficult to answer?
I know I cannot expect these sediments to weather and mineralize the soil and water at a constant rate or one that is predictable in anyway. I would also have to assume the minerals produced by the weathered sediments were of the appropriate make up and proportions to balance redox in the water and soil. I am thinking I should follow the recipe I have and see what happens over time testing NH3, NO3, NO2, TDS, KH, GH, pH, and Redox Potential as the soil and water age. Not that I don't think this will eventually work out but to understand how these variables are being effected as this idea becomes a reality. While keeping an eye out for nutrient deficiencies, root rot as time passes, or anything else that effects life inside the aquarium.
Because of the heavily oxidizing environment of decomposing organic matter. I will use wonder shells, GH booster or Montmorillonite Clay if need to raise ORP, keeping gas exchange rates and O2 levels as high as possible, using a UV sterilizer, high intensity lighting, heavy planting of fast growing plants from the beginning, and aggressive pruning to reduce the need for water changes to once a month or less are all things I will do. It will either work like expected or not. I will be able to keep ORP in an acceptable range or I won't and then I will have to use other tactics to raise ORP. I am confident that I will be able to grow rooting plants very well after the soil is built. Given time to reach equilibrium, and nutrient cycling, nitrifying, denitrifying, and carbon oxidizing bacteria are given time and appropriate conditions to multiply the soil will be ready to plant in.
Now what is an acceptable redox potential for aquatic plants is very different from what is acceptable for healthy redox potential in water for fish. Specifically for me, guppies that like higher concentration of Ca and Mg as well as above average GH leading me to think they like a higher water ORP as well. I have read that redox potentials for waterlogged soils is usually very low as well as pH, due to the lack of cations and O2 found in these soils. I may be able to have a soil substrate with a higher ORP due to the addition of Mg and Ca from the lime and allowing it time to find an target ORP and pH range in which it fluctuates. The high CEC of the soil will allow large amounts of Ca and Mg access to the exchange sites where they can bond and buffer soil pH. The high CEC allows for more of these cations to bond and thus it takes significantly more Ca and Mg to buffer pH of high CEC soils which are usually on the acidic side as well. This means I will have a lot of exchangeable Ca and Mg for plants and animals to use when I start adding other cations to the mixture which will exchange places with this Ca and Mg making them available to plants and animals in the aquarium water as they are replaced by cations with higher binding affinity to CEC substrates. These sediments will slowly release exchangeable cations through chemical weathering caused by acidic environments in the soil and bacterial acidification of anaerobic soils in the soil organic matter, namely the peat moss. This should help replenish Ca and Mg in the soil and water then available for plants and animals inside the aquarium.
I though a long time about nutrient ratios recommended for aquatic plants and decided that it would be impossible to get exact ratios because these mineral sediments don't have a definite mineral content. Only minerals known to be in them noting definite with percentages. So I went with someone else's idea that plant do need specific ratios of nutrients the just need adequate levels of essential nutrients. Having none of the macronutrients being a limitation for growth. The thing with ratios is that some plants will luxury feed on certain nutrients if they are available to access them and this will throw nutrient ratios in the plant matter out of balance leading to what would look like deficiencies due to an over absorption of the nutrient that was over consumed. The limiting nutrient should be carbon but I don't think it will be as low as non soil tank with low amounts of carbon oxidizing bacteria in the carbon rich compost where CO2 is naturally produced. I have read that natural waters supportive of plant growth have levels closer to 10-30ppm due to organic matter present in soil and soil organic carbon being converted to CO2 in many microbial processes. Because this soil is fairly heavy in inorganic matter that is decomposing. I am going to shoot for a soil redox potential around +250 mV and a pH around 7.0. With my water redox potential target around the same and the soil with a slightly higher pH around 8.0 and hardness around 11dGH appropriate for guppies. I might use crushed coral in my canister filter to boost water pH and GH to desired levels if the wonder shell won't do it. Crushed coral will also provide Ca and Mg to keep ORP from going low due to Ca and Mg being used my the plants and fish in the tank.
I am having a hard time trying to understand my research on ORP in soil and water and how it behaves differently in waterlogged soils.
I think the soil and water will both effect each other, right? The ORP will be highest in the water column where O2 is present with high mineral content. Then over time ORP of soil will start to decrease as O2 at the surface layer of the substrate is reduced my bacteria. If I understand correctly as soil depth increases ORP, pH, and dissolved O2 will decrease.
I have found in the attached article (link is at bottom of post) this information: "By-products of aerobic respiration are soluble organic compounds, carbon dioxide, ammonia, nitrite, nitrogen gases, ferrous iron, manganous manganese, hydrogen sulfide, hydrogen, and methane. These substances are transported within the soil profile and into water above through soil diffusion, seepage, and sediment disturbances."
Some of these substances are oxidants others are reductants, right?
Do you have any idea how all of this might come together to create an ORP in the water column when using a mineral and organic matter rich substrate?
Does it come down to the total amount of oxidizers and reducers in the water column and/or soil which are hard to quantify?
Do you see anything I don't understand about my recipe or any oversights I have made applying the ingredients in the steps I have?
Will the pH buffering with dolomite lime work the way I think?
Will these Ca and Mg cations be made available for use by plants in the soil or for animals in the water when various cations are introduced to the soil through chemical weathering of the mineral sediments, pushing the Ca and Mg off CEC sites and into soil solution or the water column?
Cations in aquariums move through the soil solution up into the water column and possibly back into the soil, repeating this over and over again until the cations are needed by a plant of animal?
Thank you for you time! I hope you have a minute to answer what you can.
283.Anaerobic Soils. In Encyclopedia of Soi....pdf (466.59 KB)
