Alright, so I have two betta fish, one in a three gallon eclipse tank, and one in a 2 gallon plastic case (with plastic slitted top). They're both male crowntail bettas, they're both a little overweight, and they both have MAJOR algae problems.

I tried scrubbing the three gallon tank yesterday since it has the biggest problem, but 30 minutes of back in forth scrubbing just left me with a tiny semi-cleared patch. It's hard to get rid of to start with, and it seems to always come back at an alarming rate. I can't seem to actually get rid of it altogether even for a short time either, since the gravel at the bottom of their tanks seems to have algae near the bottom which I can't get at or clean.

I've done two doses of algae remover since Sunday but I feel really uncomfortable using it because of the cancer warning. (They say to use it once every three days until it's undercontrol then do it once a week.)

I've also avoided doing a full scrub down of their tanks because both tanks are fully cycled and I'm worried I'll destroy all that and actually end up hurting my bettas more.

Please help! I have trouble even checking to see if they're alive.

is it green or brown algae?

In both tanks it's green.

i'm not an expert by any means but i do know that sometimes the placement of a tank has a lot to do with green algae. if a tank is getting a lot of light it can cause green algae... are your tanks somewhere where they get a lot of sunlight or direct sunlight?

I agree with liz........could be too much light. How often are you changing the waters? Algae also needs nitrates to grow.

Some common causes of excesive algae growth are direct sunlight and high nitrate levels.

If you move the tank away from direct sunlight and do more frequent water changes (to lower the levels of nitrate), then scrub off what you can, the algae should be reduced. If you really work hard at it, you might be able to get rid of all of it.

Well, both tanks are in my room and therefore get no direct sunlight, and since I live in the Northwest and we're having an unusually long rainy season, any sun at all is most likely not the cause.

So I suppose it must be the nitrate levels. I've been meaning to replace the bottom of my three gallon tank which is currently gravel, with some glass marbles. I've always done partial water changes, about 30-40% at a time. Would it be wise to keep just like a few cups of the old water in my next cleaning and do a massive clean out?

I'd be terrified to do something big like that with a goldfish because they produce so much ammonia, but I mean, I'm guessing bettas are some what less messy and so a slightly weaker cycle wouldn't mean death.

Does anyone recommend doing this, or not doing this?

i dont know that it would be a good idea to change ALL of your gravel out in one shot. your gravel can hold bacteria that aid in getting your tank cycled completely. granted, your filter should house most of your bacteria but you could experience some serious water quality issues if you change out all of the gravel at once. if i were you, i would do a large water change and take out maybe 1/4 to 1/3 of the gravel and replace it with the glass marbles. then in the next water change, another 1/4 or 1/3 and so on. making sure that you wipe down the algae with each change.

I agree, I wouldn't do that drastic of a change. Concentrate on doing regular good sized water changes, and feedling less. You mentioned that they're overweight so that could be a source of nitrates and phosphates as well. What are you feeding and how often?

Well, I managed to get my picky-eater betta (the one in the smaller tank with a much milder algae problem) down to a more reasonable weight. He refuses to eat anything aside from bloodworms, but I feed him them every other day and I try to get him to eat some pellets at least once a week.

The over-weight one eats everything and for a while I just gave him more food than the picky-eater but I figured out a while ago that just because he ate it, doesn't mean he should. He eats about two or three full sized bloodworms and one or two pellets every other day.