something not right since cleaning, help

[orillionro86]

We have roughly a 45 gallon freshwater aquarium at my work. When I first got here, we had a guy that took care of it. It has the water pump that hangs on the back side of the tank with bio bag filters and a uv light filter. For 2 years this tank has performed flawlessly. The guy that too care of it ended leaving the company, so I took over care of the tank. Eventually, the gravel got pretty dirty, so I removed about 90% of the water, changed the filters, and scrubbed the whole tank, ever since then I can not keep it right. I now realize that a deep clean was not the right thing to do. The water stays mostly clear, but I have green algae growing on the glass and ceramic logs that is hard to get off. Also, the water pump chute that discharges the water back into the tank has sludge that grows on it. When I change the filters, there is a lot of sludge in the sump. I have tested the water for phosphates and its always high. I tried an additive to lower phosphates, but it just clouds to water up. What can I do to get it back right? I've read a little about cycle. Its been about 8 months since I've been fighting the tank. I thought about adding some api stress zyme. Every week, I have to add about 5 gallons of water back to the tank due to evaporation.

 

[rlederer]

I'm not sure if the tank is cycled - that means beneficial bacteria have built up sufficiently to break down nitrogenous waste from the fish. Regardless, I get the impression that all you are doing with the tank is adding five gallons a week. That means all the waste products are building up in the tank. That will, or apparently already has, caused algae blooms.

Worse, the waste product ammonia is building up in the tank and will eventually prove fatal to the fish. What you need to do is remove about 50% of the water every week and replace it with fresh water. That removes the waste products.

I don't recommend using any chemical additives to try to solve water issues. Changing the water should solve all your issues (and not overfeeding.)

Get a test kit and test for ammonia. I'm not sure what the phosphate issue is but water changing might solve that too.