Issues with Ammonia, nitrite and canister filter flow rate

[redright28]

Preliminary Info:

Tank
90 gallon closed-system with approx. 70 gallons of water

Filtration
Aquatop UV500 canister filter
Bottom/1st Tray: Blue and white mechanical filter (replaced blue filter on 8/25)
2nd Tray: ChemiPure Elite filter & ChemiPure filter, added 6 MarinePure BioBalls on 8/25 with white mechanical filter on top (replaced filter on 8/25)
3rd tray: MarinePure BioBalls stacked tighly white mechanical filter on top
4th Tray: Fluval BioMax ceramic media & several MarinePure Bioballs stacked tightly
Flow rate- 220 gph (significantly lower than rating of over 500 gph)...turnover rate is only 3.00-3.20 times per hour.

Feedings
8/18 - Began feeding fish three times daily with enough food to eat within 1-2 minutes per feeding.  Prior to this fed fish once daily, while skipping a day every 5-7 days.

Water Parameters
pH - 7.5-7.7
Nitrate -0 ppm
GH -300-340 ppm
KH - 110 -120 ppm

Medication
Treatment for potential internal bacteria (mainly in intestines)
Started on 9/3, will finish on 9/9 - SeaChem MetroPlex, NeoPlex and Focus mix in Garlic Guard and tablespoon of food pellets (added Focus as a polymer/binder and to appeal to fish).

Redox
Jungle Clear Water (Potassium Pomanganate) test showed slight reducation after 24 hours.
OSP meter reading between 190-220 mv

Issues/Concerns
1) After weekly 20% water change, Nitrate level reads around 20 ppm.  After only five days Nitrate level reaches around 40 ppm, and after seven days over 50 ppm.
I'd like to be able to keep Nitrate level below 50, so I can perform bi-weekly water changes.  Is this realistic since I am now feeding them three times daily?

2) I am having a hard time keeping Ammonia levels below .10 ppm over the past several weeks.  Tested on 9/4 with SeaChem Total Ammonia Test (30 minutes result .05-.10).
Tested again today on 9/6 with SeaChem Total Ammonia Test (30 minute result .15-.20).
I'm thinking this is caused due to an increase of mulm (waste & food in the tank) due to increased feedings; however, I do remove waste as I see it.  Vacuuming during water changes has shown an increase in mulm in the tank too.
Is the poor filitration flow rate a cause of this issue?  Is the replacement of the blue & white filter together on 8/25 another cause?  I've added Prime and will continue to do so until reading fall under .10.  How to I get these numbers in line?
Do I need to increase filtration flow rate?

3) As stated above, my filter is functioning at less than half of advertised flow rate.  Do I have too much filtration? Will increasing filtration rate help with Nitrate & Ammonia readings?

Thank you!
Greg

[devonjohnsgard]

It's normal for a canister filter to have about 60% less filtration than advertised on all canisters. I believe it's due that they rate the canister with nothing in it, then adding the media and it getting dirty over time slows the flow.

I would add your chemical filtration to the top of canister. Course-fine bottom up, with chemical on top.

Likely you removed some good bacteria by replacing the pad. Though .15-.2 is pretty normal reading. I believe that ammonia test is reading ammonium as well?, you might want to get the ammonia alert from seachem and it just reads ammonia.

[Carl]

I agree with Devon's points, in particular as to the set up of the filter which is not correct for optimum flow and filtration.
Ceramic Media and Bio Balls should be at the beginning.
As well, I am not much of a fan of Bio Balls, especially in a canister filter.
I would use AAP Matrix and/or Volcanic Rock instead.

Further Reading:
www.aquarium-pond-answers.com/2007/05/aquarium-filter-media.html

Running an easily rinsed AAP Filter Max # on the intake of the filter would also be advisable.

Other tips for nitrates include:
Algone (in the top of your canister filter)
Purigen (I prfer this over Chemipure)
NPX Bioplasitics run in a FSB filter
& of course water changes

Carl