I have a 20gallon established aquarium, with guppies nad baby guppies. I clean my tank regurally. I know the bacteria isnt breaking it down because before as the ammonia was broken down the nitrates would go up. But the nitrates have gone down and havent changed for about 3 weeks now. The ammonia is getting really bad though. Im down to feeting the guppies every other day even though thats not good for the fry, but i have no choice. Is there anything im missing that I should be doing?I have a ammonia problem in my tank. the bacteria isnt breaking it down and i do 25% changes every other day.?Have you tried lowering your water's P.H. with an artificial agent? To reduce ammonia, you need to get your PH level under 7.0. It's a quick way to do it that will minimize the stress on your fish. You can find a PH adjusting kit under 5$ at your pet shop.
You could try a radical solution and change 50% of the water with a backup that you keep in reserve in a spare tank (but I suppose you don't have one).
Do you have a lot of animals and plants in your aquarium?
Is your ecosystem complete with cleaning fish (or shrimp)?
****************
Edit: Grodhi's idea is excellent... but cleaning the gravel will mean Maximum stress on your fish. If you decide to do that, make sure you have, at least, a nursery tank for the baby guppies!I have a ammonia problem in my tank. the bacteria isnt breaking it down and i do 25% changes every other day.?The bottom of your tank (in the gravel) may be your problem. Get yourself a siphon type vacuum for the aquarium and gently clean the gravel. If you only do partial water changes, you're not removing the source of your problem.I have a ammonia problem in my tank. the bacteria isnt breaking it down and i do 25% changes every other day.?your ph may be to high, u need to get a sample of water and ask your pet store people to test it. it works, and are u cleaning out the gravel with a python\siphon. and having high ammonia will not mean your fish will dye. some how my fish made it through a ph of 9.0 and above when my fish only need a 7.0. the pet store people say my lv to to high but my ph level in my tank says its 6.6 so anyway clean the gravel and test your ph.
