The Puffer Forum

20 gallon tank with a single striped red eye puffer. She is fed half a cube of bloodworms every other day, last water change was two weeks ago, 10ppm nitrate, 0.50ppm ammonia, Ph of 7.6.

Our problem seems to be algae, it looks like it could be blue-green algae but we aren't sure. It first appeared _ weeks ago and was siphoned out but return with a vengeance, it has now taken over a good portion of the sand at the bottom of the tank. It appears as bluish/dark green spots on the sand. Is this really BGA or something else and what can we do to get rid of it?

have you tried a black out and reduced feeding?

.5 ammonia usually = too much waste

Yes! I have the exact same thing trying to overrun my tank. I think it's a cyanobacteria, actually, and from what I've noticed it tries to flare up whenever there's excess phosphates in the tank. It starts by growing a green patch here and there on different spots of the substrate but will quickly cover it if not kept in check. What it doesn't seem to understand is this - my tank, my rules - and nothing grows without permission.

There's a few things I do to stop this garbage from growing in the first place. The first one is control of phosphorous levels. Common sources of phosphates are tap water and uneaten food, especially live foods like bloodworms, shrimp, krill... you get the idea. Organic tissue, by design, contains a lot of phosphorous, so removing uneaten foods is essential. A turkey baster works really good at this. As far as the tap water goes, try using some reverse-osmosis water for your next few water changes if you're not already, and see if that doesn't help.

Another thing you have to think about (and a lot of people don't) is the sand in your tank. One gallon of water weighs a little over 8 pounds, and all of this weight sitting on top of your sand will pack it down, then it goes stagnant and... stuff... starts trying to grow on it. I use fine aragonite in my tank so I have this problem myself, and my weapon of choice against stagnant, packed down sand is my faithful sleeper goby. Not only is he a little pig that will eat anything and everything that my puffer doesn't get to, but he also sifts the sand and keeps it so stirred up that nothing gets the chance to grow on it. Adding some sort of sand sifting critter to your tank would probably help quite a bit.
Whatever this green stuff is, keep scooping it out. If it is a cyanobacteria it will start competing with your puffer for the oxygen in the water, and it will win if allowed to grow.

Minor correction: Cyanobacteria geenerate oxygen by photosynthesis, just as algae and higher plants do. They are responsible for a non-trivial percentage of the O2 in our air.

Phosphates are required by plants and animals, including fish. They cannot be excluded from living systems. But excesses can and do promote algae and cyanobateria. Once the cyanobacteria develop a decent biofilm, they can re-cycle phosphate with their biofilm complex quite well with little or none detectable PO4 in the tank water.

We've been scooping it out as much as possible and it doesn't seem to be doing any good. The tank gets a siphoned almost everyday to remove any waste and left over food at that time we also stir up the sand a bit. We asked a guy at out lfs who told us the name of a algaecide but if possible I'd rather not use chemicals. A 50% water change was done as soon as this was posted yesterday as well as another cleaning.

Do you have a phosphate test kit? Nitrate and phosphate reading together would help.

Have you vacuumed all possible BGA out and done a minimum 3-day blackout?

Algaecides will not affect BGA. It is not an alga, it is a bacterium. Maracyn (which is erythromycin) will kill it after as complete as possible removal.

Increasing the current will help avoid a recurrence..

What is the lighting on the tank and how long is it on per day?

We do not have a phosphate test kit and haven't done a blackout but were planning to if that's the best option. I'm sorry but I don't know what the lighting is but its on for maybe eight hours a day, I'm not entirely sure as the tank is at my boyfriends house not mine.

I would suggest the good clean-up with a 50% partial, then treat with Maracyn (NOT Maracyn2) and a 3-day black-out. Afterward check for any dead cyannobacteria and siphon it out also - if any is present

Do you have any feeling for the current in the tank?

The current was crap, that I know for sure, the filter that was on that tank was dying but was replaced saturday evening. With the new filter the current has picked up a bit, the best way I can think to describe it is like a slight breeze in the tank. The plants sway just a little but are otherwise still. We try to keep the current somewhat low as the puffer stresses easily.

You need to be doing more WC. Why are you showing any ammonia at all? What's the nitrite? As RTR mentioned get a phosphate test kit. When I had an algae problem in my reef tank, I found it to be up to 3! It should actually be .01-.03

Very roughly, in planted tanks (or SW invert tanks) the N:P ratio should be ~7-10:1. In unplanted FW tanks, both should be as low as possible, but as PP implied, phosphate in whole numbers is almost always an invitation to algae or cyanobacteria explosions.

Phosphate at undetectable levels may be too low - both plants and animals require phosphate for life. But excess can give tank issues big time.

We are starting a blackout tomorrow and will look for a phosphate test kit.