Oldman47 (not that old) likely has nailed it !! Sounds like by using the ammonia remover, that you have not allowed the good, nitrifying bacteria to thrive. They thrive off of ammonia and then covert the ammonia to nitrites and then nitrates. Of those three, the ammonia is the most poisonous. In a well established tank, there should be ZERO ammonia -- not "acceptable" levels as you say in your orignal post.
Cleaning out your entire fish tank, replacing the gravel and cleaning the filter, is the WORST thing you can do -- as you have completely removed the nitrifying bacteria and the tank has to cycle all over again. A new tank will have a rise in ammonia, before the nitrifying bacteria becomes abundant enough to convert it to nitrites and nitrates. You can help with adding commercial preparations that add this nitrifying bacteria. I just started a new 75 gall tank -- and it took 2 weeks before my ammonia levels came down to zero. Make sure you are vacuuming/siphoning the gravel to remove uneaten fish food and fish poops -- both which are sources of ammonia. Keeping up with this will drastically decrease the pollutants in your tank. Depending on how many gallons your tank is, how many fish you have and how much food you're putting in, you will have varying amounts of ammonia being produced. Add too much food or dont' vacuum enough, the nitrifying bacteria, which lives on all surfaces - gravel, ornaments, plants, filter medium, etc -- will not be able to keep up with the amount of garbage in the water. Also, the chorine and chloramine neutralizers can also bind up oxygen in the tank - so make sure that you have plenty of air bubbles going. You may want to check with your local water company and find out how many ppm (Parts per million) they are adding of chlorine and chloramines. You may find, as I have here in Florida, that you need more of the dechlorinator than what is recommended by the manufacturer. I find the most common reason for fish dieing is ammonia poisoning due to over feeding, not enough vacuuming the crap from the gravel and/or insuffience water changes. Remember your ammonia should be zero level at all times and if it's not, then there's too much food and poops,
Mike
Cleaning out your entire fish tank, replacing the gravel and cleaning the filter, is the WORST thing you can do -- as you have completely removed the nitrifying bacteria and the tank has to cycle all over again. A new tank will have a rise in ammonia, before the nitrifying bacteria becomes abundant enough to convert it to nitrites and nitrates. You can help with adding commercial preparations that add this nitrifying bacteria. I just started a new 75 gall tank -- and it took 2 weeks before my ammonia levels came down to zero. Make sure you are vacuuming/siphoning the gravel to remove uneaten fish food and fish poops -- both which are sources of ammonia. Keeping up with this will drastically decrease the pollutants in your tank. Depending on how many gallons your tank is, how many fish you have and how much food you're putting in, you will have varying amounts of ammonia being produced. Add too much food or dont' vacuum enough, the nitrifying bacteria, which lives on all surfaces - gravel, ornaments, plants, filter medium, etc -- will not be able to keep up with the amount of garbage in the water. Also, the chorine and chloramine neutralizers can also bind up oxygen in the tank - so make sure that you have plenty of air bubbles going. You may want to check with your local water company and find out how many ppm (Parts per million) they are adding of chlorine and chloramines. You may find, as I have here in Florida, that you need more of the dechlorinator than what is recommended by the manufacturer. I find the most common reason for fish dieing is ammonia poisoning due to over feeding, not enough vacuuming the crap from the gravel and/or insuffience water changes. Remember your ammonia should be zero level at all times and if it's not, then there's too much food and poops,
Mike