If your numbers are 0 for ammonia, 0 for nitrite and with your bioload..40~60ppm of nitrate is within norms. What is your Ph? Is it below 6.5? If it is..its too acidic...although the "norm" is 7.0 Ph for neutral..aro's adapt to a little acidity...hence 6.5.
1) Also is the Ph constant or does it fluctuate a lot?
2) Have you recently cleaned your filter or turned of filtration for a period of time?
3) When was the last time you cleaned your filter pads/gravel?
4) What is you tank's temperature?
5) Are you using carbon for chemical filtration?
6) Do you do scheduled water changes and how much?
If already is fine, 0 ammonia, 0 nitrite, steady Ph you should be okay, except for all the medicines you dumped in. Cloudy eyes ususally clears up if the you add aquarium salt as per instructions on the box, crank the temperature up a notch or two. If its ich...you crank up the temp a little higher..ex: if you tank is constantly @ 80 F, crank the temp up to 83~86 F.
Lastly, if you have a properly set up tank that is fully cycled you don't need carbon in you filter on a constant basis. Only time charcoal should be used is when removing medicines. I'm sure most of the people here don't use any carbon to maintain a healthy and clean smelling tanks. Thing with carbon, if you don't change it depending on your bio load...over time it gets oversaturated and leaks back the impurities into you water. I can't remember where I've seen this article..but it describes how the effects are harmful to the fishes since the impurities leaking back are by products wheres the original "junk" is taken by the carbon and is converted.
Something about "adsorption"...can't really recall.
I don't know about your routine for water changes only you do. But with all the inhabitants you have, its a good idea to do a w/c at least once a week of about 30~50 percent, of course you might want to age the water properly and try to keep it within the same temp as the tank water. Remember in the warmer months the water tends to get really nastier...so a w/c twice a week is not uncommon. But that is all based on your room's ambient temperature..does it get warmer or is it always a constant temp in the room.
Anyhow...good luck on your tank/fishes.
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