How to suppress algae in my freshwater tank?

I’ve got a 45 gallon fishtank with a single 4’ florescent bulb over it.

I recently added a half-dozen platies and two snails and all but one platy slowly died over about three weeks. The snails went first, FWIW.

I took some water to the store and they suggested that my Nitrates were a bit high and I should change what chemical I’m using to pre-treat with my water changes (from Aquasafe to Prime) and that I add some salt to the water (I had none before).

Perhaps related, perhaps not, I seem to have a pretty strong algae layer growing now. I scrubbed the glass yesterday, but the plastic plants (no live plants) are still pretty heavily covered and the inside of the tubes from the under-gravel filter to the power heads are layered, too.


We have snails in our tanks, but the tanks aren’t that big. Funny that your snails die, we have to kill off large numbers of them because they become too numerous and make the tank ugly. We don’t even buy snails, we just get some live plants from the pet store and they usually have a couple of snails on them that end up breeding until there is hundreds.

If you are just starting up your tank, it will takes weeks for the right balance of bacteria to develop. That may be why your fish died.
In general, nitrate levels rise quickly when you overfeed the fish. It’s amazing how little food they need.
Algae will grow when nitrates levels are high and the light is on all the time. Make sure the light goes off at night.
That being said, algae growth is a good sign in a fish tank. Scrub it away during your weekly cleanings so that you can see through the tank and enjoy.

The light suggestion was pretty much what I was going to say. Using a timer to shut it off for at least eight hours at night could significantly reduce the algae.

Yeah - got the light on a timer, it’s off 10 hours a day. The tank is fairly well established, its been in-place since April. When we moved it here in April, we saved 10 gallons of the old water and all the wet gravel so the base bacteria should be pretty good.

There’s 8 tetras, a couple silver dollars, & two gourami, and one pretty big catfish. Inches of fish suggested we could handle a couple more so we got a small school of platies to add some color. We were looking at something that might like to hang out at the top of the tank.

Perhaps I’ll just put label the algae a “good thing” as Solkoe suggests and keep scrubbing.