freshwater aquarium woes

Question
My daughter has a 50 gallon aquarium with quite a few fish in it ranging from 16" plecostomus to guppies. She has had the aquarium for years and some of the fish are quite old. The past year she has been unable to get the water to clear and has recently noticed tiny white organisms on the underside of the tank cover and light. Thousands of them, barely visible to the naked eye, but definitely there! We have tried parasite meds and water changes to no avail. Fish have been dying regularly now and we don't know if this "organism" is what is killing them, or if it is actually in the water too, causing it to be cloudy. Also, could this cause harm to humans?  We have removed all of the gravel from the tank and left it out, and have changed the filters several times a month. We don't know what to try next and are a little nervous handling the water in case we catch something... Is there anything else we can do?  The PH has been very hard to regulate as well.

Answer
Hi Lindi,
The tiny organisms sound like planaria. These worm-like creatures are very common in aquariums that have a high nutrient load. In this case it would definitely make sense because large plecostomus produce quite a large amount of waste and can overwhelm the aquarium very quickly causing an over abundance of nutrients that both planaria and the bacteria that cloud the water are feeding on. Neither are harmful to humans. But their presence means that the aquarium is full of pollutants.

It sounds like this aquarium just needs a lot of extra care to get the system balanced. With every cloudy water problem and planaria issues I've always had the best luck in starting a strict water change schedule. This basically means that to treat the problem right now ive found the best way is with daily 50% water changes.  It helps to have a python no spill cleaner for doing water changes like this on a big tank.

Also keep in mind that with removing the gravel . A large portion of your bio filter has been lost. AKA the good bacteria that develop on the surfaces of the tank like the gravel bed. You could be having some ammonia issues along with everything else. Which would explain the fish loss. You can get all the important levels checked by most pet stores. These levels should be as follows- ammonia-0 nitrite-0 nitrate-20 or less

Right now, water changes are your best bet in dealing with all these issues. It may take a little while, but patience and persistence pays off. Be careful of chemical cures that the pet store may try to sell you. They have never worked for me.

Best of luck and I do hope this helps!
Susan~