High nitrates - overstocked??

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gonnelro

Feeder Fish
MFK Member
Feb 14, 2008
324
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New Jersey
I was wondering what you guys think of this. I have two tanks, a 72 bow and a 90, which are having very high nitrate readouts consistently. I do large water changes once a week - 40 gallons on the 90 and 30 on the 72. However, my nitrates read out literally off the chart before the change and at around 100-150ppm after. First, is it possible that I let them get out of control a while ago (I used to do water changes less frequently before I realized the whole nitrate problem), and the level is so high that I would need to do like a bunch of small changes daily to lower it, and then go back to my weekly regiment? Either way Im planning on doing that soon. What about overstocking? This is what Ive got:

72 bow:
1x 8" gold severum
1x 8" arius seemani (columbian shark, black fin shark, whatever)
1x 6" rainbow shark
1x 4" king tiger pleco
1x 10" sailfin pleco (L196)
2x 3" gourami
1x 5" blood parrot

90:
1x 13" silver aro (going to move to a bigger tank when he gets to 2')
1x 5" EB Jack Dempsey
1x 9" arius seemani
1x 8" black ghost knife
1x 6" irridescent shark
1x 8" common pleco
1x 4" albino bristlenose pleco

Anyways, thats what I got, and I thought that the weekly changes listed above would be able to keep the nitrates down, but they havent. I have good filtration in place, so no ammonia or nitrites, and I dont think that I overfeed. I feed them regular flakes, bloodworms, brineshrimp, krill, prawns, massivore, algae wafers, and zuccini for the plecos sometimes. the food matches to certain fish (I mean I feed the bigger stuff mostly for the aro). So am I totally overstocked? And I know that the aro will get huge some day soon and will definetly need a new home, so dont worry about that. But for now, besides doing 20% changes every day for a week, and then checking the nitrates to chart the buildup and finding out how often I need to do changes, or just cutting down on feeding, do you guys have any pointers?
 
Yeah, you got big fish with big appeitites, so you're going to have a big bio load.
but, if you say you don't have ammonia and nitrites, then your filers are doing it's job.
Nitrates are the end products of bio filtration. Have you thought about using plants in your aquarium or your filter set up? Or large water changes every 2-3 days should help.
 
You will need to increase the amount and frequency of your water changes. What about the pH in your tank compared to the tap water? This can also be a concern with heavily stocked tanks.

I would do a series of daily 50% water changes until the nitrates are at 20ppm after the w/c. Once you get to that level scale the w/c back to one 50% a week. Measure the rate that the nitrates rise. If the nitrates rise to 40ppm in a week then you can probanbly continue with the one 50% a week. If the nitrates rise to more then 40ppm you mat want to try doing two 33% changes a week. You will eventually be able to customize your w/c schedule so that nitrates will never be above the 40 ppm level.
 
Also I don't know what type filters your running. But if you clean the mechanical media on a weekly basis, this will also help in keeping nitrate levels down.

On another note, you gonna want your aro in a larger tank much sooner then when it gets to be 24".
 
Thanks guys, thats pretty much what I thought. And I dont know about plants, honestly, right now I dont have any money and I would have to get new lights, buy the plants, etc., so Im going to stick with the daily w/c until I get to 20ppm and chart the nitrate rise from there. Another question though, nitrates are bad for fish, but if I waited until May to do the daily changes for a week, you think Im making a very bad decision? I have absolutely no free time (get out of the house at 7am, home at 11pm every night until mid-May). I know I should do it now, but my fish are all healthy, eating, etc. No real signs of stress, even growing despite the nitrates. Think they can ride it out another month? And I know thats a loaded question without a real concrete answer available, but indulge me
 
I would be worried about a pH crash myself.
 
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