This is easy enough to fix.
First, fill a glass with tap water. Test for ammonia. If the ammonia level isn't zero, then your tap water has ammonia in it. Note that some water has chloramine added to it instead of chlorine. Chloramine can produce false positive readings with ammonia test kits. Either way, use a water conditioner that neutralises ammonia AND chloramine. Once you've done this, you can be sure the water you're adding is safe. Make sure water changes are relatively small (no more than 20% at a time) and the biological filter should be able to remove this ammonia without causing your fish any stress.
Second, if your tap water has no ammonia in it, but your tank does, then the problem comes from the livestock. Essentially, the filter isn't up to the job. If a filter can process 10 units of ammonia per second, but your fish are making 10.1 units per second, then you'll always have some ammonia floating about in the water. Increase the amount of biological filtration by adding a second filter. Even if the ammonia comes from the tap water, your biological filter should be able to "make it go away" within a few hours. So persistent ammonia readings imply poor biological filtration. Review, and act accordingly.
Cheers, Neale
well the tank is fine minus an amonia problem that i cant seem to get ahead of, but other than that all of my fish are happy and healthy.
the tanke has an emporor 400 and 280 on it both with amonia crystales in the media slots, but with some more water changes the tank has started to become clear, todays change made a huge difference, also due to his size i gave my pleco to a freind and that lowered my bio load by a huge amount. might go for a royal next, but i dont know yet, up for sugestions.
^^ that was my 36 gallon by the way not the one with the elephant nose in it, im beggining a heavier water change regiment on that tank tommorrow morning, should be clear by easter.