Control of ammonia in goldfish tank

Question
I have 2 goldfish (4 in and 2 in)& a sucker fish in a 10 gallon tank with a 20 gal filter pump, an airstone, and an underwater pump. The tank has a few live plants and one large decorative log. Problem: Dangerous Ammonia Levels! Weekly: I change 50-60% of the water and take out the gravel from the tank and rinse it well; I change the filter every 2 weeks, but I still have problems with ammonia. I feed the fish goldfish crisps 2 times per day. I'm concerned the ammonia is going to kill my fish. Please help! Thank you for your response. Lydia

Answer
Hi

Ok first things first, when you say you "change the filter every 2 weeks" do you mean you rinse it out and clean it or actually physically change it for a whole new one? A filter shouldn't be physically changed every 2 weeks. In order for your fish to survive in a tank, Beneficial Bacteria (BB) must build up in your tank. What this BB does is help conver the ammonia to nitrites and then into nitrates and then when you do water changes on your tank you take some of the nitrates out, this helps stop your tank becoming toxic for your fish and killing them.

If you are pyhsically replacing your filter every two weeks with a new one OR even just replacing the media IN your filter every two weeks, what you're doing is killing off any BB you have built up in your tank. Every SECOND water change, you should wash your filter MEDIA out in water that YOU HAVE TAKEN FROM YOUR TANK. What this does is clean the media but not kill the BB. Tap water kills BB quicker than anything and alot of people, without realising this, regularly wash their filters and filter media under the tap and kill of any BB that has built up, therefore sending their tank into a cycle. (A cycle is Ammonia - Nitrite - Nitrate = water change).

Do not take the gravel out and rinse it either, this also holds some BB and by giving it a good clean every week, you're killing off more BB.

Invest in a Gravel Vac, this cleans your gravel without taking too much BB out of it and also does a water change for you.

Also cut back on your feeding. Feed once a day, about the amount of their eye, this is roughly how big their stomach is. Goldfish do NOT have the ability to register when they are full and so will keep eating as much as you are willing to feed them, which would only add to your ammonia problems.

HTH