Ways to remove DOC from water?

[hwofnt]

What ways to remove dissolved organic compounds (DOC) from the saltwater are most effective and cost efficient?

Best known (for me) are:
1. Protein skimming
(foaming action, noise, electricity, questionable efficiency, overflowing).

2. Activated carbon
(adsorption, after all capacity was used carbon should be replaced by new, smell for a fish).

3. Ion exchange resins
Chemi-Pure, Poly-Filter, Purigen and others.
(Cost, speed of action, targeted type of compounds).

4. Bacterial compounds, not nitryfying
(high cost, efficient skimmer is a must).

5. Massive water changes
(high cost, space and work, unless you live near the ocean).

That is usually enough for a common aquarium, but if the feeding must be much higher, say, for a sun corals tank - when daily or twice a week 75g tank should process 30 cubes of food, problems rise.

Even 8 washed cubes can make tank a mess - even with micron bags, 2x oversized skimmer (ASM G-3, not Shorty II or Bubble King), and carbon.

I even tried rated for 250g tanks ASM G-3 skimmer on 6g tank with 6g sump - barely enough to contain this skimmer, all the same. There was article that skimming removes only 20-30% of DOC, then it is explainable.

In addition, home-made meaty food (you know, Adam Blundell's or Melev's recipe), pre-washed or not, makes skimmer overflow fast. And sitting for an hour after feeding and cleaning cup and re-adjusting skimmer - waiting again until it stabilizes for the 2 hours - is not an application for real life.

I asked on other forum, was eventually told that they don't know what my problem is. Other sun coral keepers, more successful ones, had more high end skimmers and used these advanced bacterial and enzyme formulations, and a whole food like mysis, not a shredded shrimp.

Any ideas are more than welcome.

[Carl]

I agree with the thought/comment that Skimmers can only remove a percentage of DOC (what the percentage is, I am not sure, as this can vary IMO).
Adding ozone to a skimmer can improve its efficiency, but make sure the ozone does not escape to the aquarium.

Using Micron filtration/cleaning devices such as Vortex filters or better the Aquarium Cleaning Machine can help remove DOC.

I have observed (as have others) nitrates go down as well as more stable KH (without added buffers) with the use of this device over simply changing water with a gravel vacuum or Python.
I will admit that these observations were mostly made in freshwater, however I think this is an easier observation to make in freshwater since most marine tanks have regularly added buffers or well buffered salt mixes used. As well most marine tanks are generally maintained with lower nitrate levels (making observations/tests more difficult).
In freshwater tanks, KH is often much lower, so DOC can have a more direct affect on KH (& pH) making these observations more noticeable.

When it comes to controlling DOC, no one method should be used, but as many methods should be employed until you are comfortable with the results.

Carl

[hwofnt]

I was re-reading article about how much skimmer can remove
and stumbled on the other one, about activated carbon (1). Looks like activated carbon removes more than skimmer.

They posted amount of carbon (2), efficiently removing most of DOC (without adding new pollution ;D ), for the clean and dirty tanks 75 gal +. Activated carbon in amounts below 75 gr was not efficient, 100-150 gr worked well for any size of tank.

One problem: we are measuring it by cups or tablespoons, without having any idea how much it will be in grams. Do you have this information, by any chance? How many grams will be the cup of, say, Black Diamond Activated Carbon, or other of the same class?

Your advice on amount of use and frequency of changes?
Thanks.

[Carl]

First interesting article, thanks for sharing!

While I often think Protein Skimmers are over rated by many in the aquarium hobby (often touted as essential equipment, which although very useful, technically they are NOT essential), they are however an important part of the marine aquarium filtration "puzzle", which includes many other aspects such as carbon.
I should also note that in the test for TOC (in one of the articles) the article tested immediately after feeding, might observations of the use of protein refraction is that the results are not immediate (such as in a new tank with added bio load where as it often takes some time to fill the foam cup), so I would be curious as to the results if tested a few days later with no subsequent feeding added.

As to carbon, this is a subject along with the use of salt in freshwater aquariums that seems to draw some extreme views in subjects with no simple black & white answer.

Carbon can a does trap DOC, however since our primary concern is the larger more complex molecules that eventually lead to higher nitrates; that these molecules are also not trapped as deeply as smaller molecules and thus can be released as well.
The high pH of marine aquariums also affects the ability of carbon to absorb DOC, which is why I have not seen as good of results with carbon in marine aquariums (I still use carbon, but only as a part of the over all DOC removal "attack" plan.

How much carbon to use depends upon the type, the amount of DOC produced, your pH and other filtration devices/methods employed in your aquarium.
My suggestion is to measure parameters such as nitrates, alkalinity (KH), or even test TOC if you have the equipment and add the amount of carbon and change the carbon according to your results.
I personally have used a couple teaspoons per 10 gallons, changing this carbon monthly, however this is not a scientific method, rather an admittedly anecdotal method that has worked for me along with the use of other chemical filter media, other filters, water changes, etc.

Please see this article that has some helpful information about carbon (I recently updated the article as well):
Aquarium Answers; Filter Media, Carbon

Carl

[hwofnt]

The article about protein skimmer TOC removal is here, Quantitative Evaluation of Protein Skimmer Performance, just in case. While I can't expand my collection of protein skimmers to $500-$800 skimmers, I can reduce size of the tank and make sure that water flow is sufficient.

That was "driving to the absurd" trial: ASM G-3 skimmer, rated for 250g tanks, on 6g tank plus 7g sump. Heavily fed sun corals tank:


Not much difference with Rio Nano skimmer, that I started this tank with:

only the cup is larger and possibility of adjustment during overflowing exists.

Ended up with 75g rated ASM Mini, smaller, skimmer: some adjustability, takes less space, uses less electricity and costs less:

Not much help when feeding pre-washed chopped shrimp, fish, mussels - a lot of foaming and thick film that looks like coagulated protein film during soup cooking - but this is better than nothing. Not oily whole food (mysis) doesn't produce such effect, much cleaner, but costs more, if you are feeding 8 cubes at one time.

All with carbon, naturally, and phosphate remover.

With less fed tanks I tried Purigen, that was supposed to bind nitrogenous waste before it becomes nitrates, but maybe the speed of binding was low - it continued to be more or less white, yet water quality was not affected noticeably. Not impressed, but it worked well for others on common reef tanks.

To compensate feeding of 8 cubes, there should be used a lot of Purigen, that makes it cost-prohibitive, together with Prodibio that I didn't use yet.

And I also wanted to ask:
Do you know if there are commercially available TOC or DOC tests/equipment, in affordable price range?

Thank you for the information, really appreciate that.

[Carl]

And I also wanted to ask:
Do you know if there are commercially available TOC or DOC tests/equipment, in affordable price range?

I will look into this.
What are the measurable parameters you are attempting to correct with the Protein Skimmer?
I am really not sure that such a device is worth the cost.

The article about protein skimmer TOC removal is here, Quantitative Evaluation of Protein Skimmer Performance, just in case. While I can't expand my collection of protein skimmers to $500-$800 skimmers, I can reduce size of the tank and make sure that water flow is sufficient.

While admittedly I have "fast read" the article, I not agree with the conclusion.
First of all the article claimed that Protein Skimmers regained life as a device for reef tanks in the early 1990s.
This is simply not true, I and others (including large scale operations such as Quality Marine USA have been using Protein Skimmer dating back to th 1970s.

I personally was not impressed with the results of many of the air driven models such as the Sanders from Germany that was very popular in the 70s & 80s (although the addition of ozone would improve results). However the larger industrial models that Quality Marine USA employed provided more measurable results.

I have used ( & know of others that have tested even more models than I have) and seen different results.
You noted the use of a Rio Nano Skimmer, which is a very basic skimmer, am I correct in reading that your results with the ASM that the ASM G-3 skimmer did not achieve any better results?
If so what were your measurements to determine this?

Another question is that if results with different skimmers was not discernible (besides testing methods), what other filtration is on this tank, I only see live rock?
Not that just live rock and a skimmer cannot work (it can), I have ponder the question that maybe the organic wastes to be removed by protein skimmer are not in molecularly readily available form. Protein Skimmers cannot remove ammonia, nitrates, or other non hydrophobic molecules.

The article did find much difference between skimmers, however I have found the skimmers with small bubble size (more surface area for refraction) and a larger column of water will work better.

BTW, I made two videos touring Quality Marine USA:
Quality Marine 2
Quality Marine 1

Carl

[hwofnt]

Sorry, I didn't meant to step onto the sensitive toe with my notes on skimmers

Just basic assumption that skimmer has to do some useful work and not to be a purely decorative item. If it cleans something - before it was converted to nitrates - then as a result of its use water should be cleaner. Measurable/ perceptive parameters of water quality for average hobbyist are, as far as I know, are nitrates, phosphates, yellowing of the water. Phosphates are removed by liquid phosphate remover, yellowing - partially - by carbon.

Only doubled amounts of carbon were not able to handle all organics introduced with feedings, I would like if skimmer took part of the cleaning on itself.

I don't have numbers at hand - too many of them and no time for a search - but with feeding by homemade mix rise of nitrates was quite big within one week. Measured by API test kits. Difference was, but not that big.

Phosphates rose too - if not use remover, but as I understand skimmer doesn't help much with phosphates.

Other methods of filtration are micron sock, changed daily and within hour after feeding. You can see bag of phosphate removing media near big skimmer, later liquid phosphate remover was employed, more cost effective. Skimmer and biomedia. Did I miss something? You made me worry, I was fairly sure that everything possible was done. UV for every tank, especially nano and without fish, is too much for my budget.

TOC measuring device - if it is uncommon and costs above $30, it likely not worth the troubles for me.

[Carl]

Oct 12, 2009 7:25:04 GMT -5 hwofnt said:

Sorry, I didn't meant to step onto the sensitive toe with my notes on skimmers

You did not step on any sensitive toes with your concerns

In fact if you were to read my posts or speak with me over the years, you would know that I often think Protein Skimmers are over rated. In fact I left a couple of forums after what I call the "Reef Keeping Police" attacked/flamed me for daring to note that Protein Skimmers were not essential equipment.

My concerns were that the referenced article had historical inaccuracies and the tests were simply not what I and others have found. Although Protein skimmers are still often over rated (which you have found), they also have improved much over the years (in the 70s I would rarely use them as the hassles often override the barely discernible improvement in water quality).
I simply view a Protein Skimmer as PART of a good marine reef system, certainly not the end all of filtration as some view them

Just basic assumption that skimmer has to do some useful work and not to be a purely decorative item. If it cleans something - before it was converted to nitrates - then as a result of its use water should be cleaner. Measurable/ perceptive parameters of water quality for average hobbyist are, as far as I know, are nitrates, phosphates, yellowing of the water. Phosphates are removed by liquid phosphate remover, yellowing - partially - by carbon.

Carbon certainly removes the yellow in the water, as well as many DOC, however as with Protein Skimmers the hydrophobic attraction (or lack there of) can make a difference in whether either remove many contaminants

Only doubled amounts of carbon were not able to handle all organics introduced with feedings, I would like if skimmer took part of the cleaning on itself.

I don't have numbers at hand - too many of them and no time for a search - but with feeding by homemade mix rise of nitrates was quite big within one week. Measured by API test kits. Difference was, but not that big.

Phosphates rose too - if not use remover, but as I understand skimmer doesn't help much with phosphates.

Other methods of filtration are micron sock, changed daily and within hour after feeding. You can see bag of phosphate removing media near big skimmer, later liquid phosphate remover was employed, more cost effective. Skimmer and biomedia. Did I miss something? You made me worry, I was fairly sure that everything possible was done. UV for every tank, especially nano and without fish, is too much for my budget.

TOC measuring device - if it is uncommon and costs above $30, it likely not worth the troubles for me.

Changing the micron sock or the use of poly pads and changing/rinsing these immediately is certainly a useful endeavor for DOC control, albeit a lot of work

Using phosphate removers should be helpful (at least as per my results).
You noted poor results with Purigen, but although this product is certainly not the end all of synthetic filtration media; Purigen is specifically designed to be an organic scavenging resin and has produced results for me as per measured nitrate levels.

PLEASE do not be afraid to ask these questions, including questioning Protein Skimmers, as we are all here to learn (including myself), and discussing this helps us all. In fact your questions helped convince me to finish an article about carbon for my Aquarium Answers website (it has been started for some time, but I never finished researching some points that were unclear):
Activated Carbon

Carl