Also, you need to realise that you can get a false positive of ammonia if you use water conditioners such as seachems prime. However, you also need to have chloramine in your source water for this to happen or you are already using it to detoxify an ammonia spike. While you will get a reading it won't neccessarily be bad due to the prime.
What is your stock + filtration + tank size?
How do you clean your filter?
Do you take everything out and wash the lot in freshwater?
Do you take just the mechanical stuff out and rinse it in freshwater?
Do you rinse everything/sponges/bio in old tank water?
Do you even use any biological media and therefore forget that mechanical (sponges/floss/etc) can and will act as your bio media in the abscence of job specific bio media? (many people forget this)
Do you even use a dechlorinator when replacing the tank water from whatever source if it has chlorine/chloramine in?
Please be truthful so we can find the source of the problem quickly for the sake of your fish. Not saying you would but some people think they shouldn't make these simple mistakes and therefore lie when asked. it is nothing to be ashamed of if you have, you are human afterall.
