algae and some death.... once again

[isoldouttojesus]

I have a 55 gallon with a Fluval 404 and two power heads on a UGF. I keep losing fish. Not like all the fish, but at least once a month something dies.

Readings are ammon = 0, nitrites = 0, nitrates = less than 20ppm. Temp is running at a constant and consistent 79 degrees. Only chemical I add is stress coat or declorinator. Water change is done every other week with about 20% of the water being changed. Lights are on at 7AM and off at 9PM. Tank receives no natural sunlight and is in a basement that is pitch black except for the occasional light in the opt of the house; otherwise we use the light from the fish tank to light the room.

The algae is brown, not stringy and grows on glass, decorations, and plastic plants. I also get this white chaulky looking stuff on the suction cups for the heater and the filter intake. It chips off easily with a fingernail or the algae scraper but comes back in about a month.

Any suggestions on what the problem is and how to fix it are greatly appreciated.

[AngelMom]

I don't think the algae problem is related to your fish deaths. Brown algae is caused by diatoms and is very common in new tanks (how long has this tank been set up?).......if the tank is not new you will need to check your tap water for silicates. For more info, you can see the link in my signature.

The white chalky stuff on the suction cups are probably minerals in the water deposited on the rubber. If it is crusty (I'm guessing it is as you mentioned scraping it off) you most likelly have some moderately hard to hard water.

Neither of these things can cause fish death though. What are the rest of the water parameters? You should also test for pH at a minimum, but info on GH, KH and anything else you test for may help. When you do your water changes, do you match the temperature of the tank water? How different are the GH and pH of the tap water from the tanks water?