Ammonia Problem

Question
Hello! First to my tank....it's a 28 gallon bow front tank with two filtration systems on it. A Top Fin 30 which came with the tank and a Penguin 200 Bio-Wheel. I also have a 14in. bubble wand in the back for added oxygen. This tank has been setup since August 2007. And has all ready gone through it's cycle which completed in September 2007.

I currently have 3 Cory, 3 Tetra, 2 Molly, 5 Red Wag, 1 Rasboro, 1 Bala Shark and 13 Fry. I am aware this tank is overcrowded, but despite that it's been ammonia free till now and I will explain why. I feed my fish a verity of different foods like: Freeze Dried Brine Shrimp, Freeze Dried Medley, Tropical Flakes and sometimes not often at all peas which they love. My PH 7.0 Nitrite 0 Nitrate is under 20 and current Ammonia is 0.25ppm water temperature is 80. Ammonia is low now because I have been doing daily water changes of 4 gallons. The problem I seem to have is once I stop it spikes again after more then a week. And the source of it was from one dead fish in December left in the tank to long more explanation below.

In December I bought 2 new fish Cory to be more specific. On that same month my wife had a new baby and the one fish must have died while we were out having the baby because I found it in the tank all ready decomposing. I was at the hospital for almost 2 day's so this fish must have died way before I got back. I immediately removed it when noticed and checked the ammonia levels. The ammonia was high about 4ppm so I did a water change large enough to lower it to about 2ppm then constantly did daily water changes till there was really no signs of anymore ammonia.

It was probably about mid January when I checked it again and realized the spike had come back but only worse this time. I went and bought some Ammonia Remover as it was now at 8ppm. This did not seem to help and in my trials I also used Amquel  which didn't seem to do much. I continued with the water changes until it was low and then stopped. Through this whole thing I did my regular weekly water changes of about 15 to 20. This was something I did regularly anyway.

So comes March and I checked the levels still have fish dying here and there as well as ammonia spiked up again to well over 8ppm. I again just yesterday did a 75 water change which again lowered it to about 2ppm. I will go with doing daily water changes of about 15 to 20, but I can't understand why the ammonia level keeps spiking up to dangerous levels when I stop. I would have thought that by now it would have fixed itself. I have also changed both filters assuming this would be OK! considering I have the Bio-Wheel with the all ready established bacteria, though I know this isn't good practice. Also when I do clean the old filters I use the tank water not tap for good reasons we both know.

I also do not overfeed the fish I'm very careful of this and sometimes I skip day's especially on weekends, because I'm usually not around. This is simply do to a dead fish, but it's now taking a toll on all my fish and by now I thought it would have been under control.

I would greatly appreciate it if you could help me. I'm not a fish expert by all means, but I did do my homework. I'm well aware of the fish cycle and overcrowding (yes I'm a victim of it, but by choice and it was under control till this mishap). I now need to get it back in order.

I will be upgrading this summer to a 46 gallon bow front since I all ready have the stand so I know this will help me out a lot, but for now I need to deal with the matter at hand so I don't lose all my fish.



Thanks,

Tony

Answer
Hi Tony:  Basically... you have something in your tank someplace that is rotting.  I would take out all of the decorations, plants, etc and give the gravel a good cleaning.  Fish waste in the gravel can spike ammonia levels.  Since you have changed 75% of the water your tank will start to cycle again... best go to an aquarium and ask them if they will give you some "dirty water"  This is a good way to help the tank cycle.  The filters should be changed when they are falling apart... the bio wheel parts... but the filter cartridges should be changed monthly... otherwise the active carbon inside of them will stop working.  Hope this helps... and please keep me posted... dave