Green sand algae

[FishyJoe]

Hi everyone, I've been away for a while since things have been going well with my fish and tank. However, for the past couple of months, as I've been vacuuming the sand, because there has been green stuff at the bottom, which I thought was a lot of fish poop (which it was), but after doing the latest cleaning, I noticed a very distinct pattern emerge of green stuff. It cannot be fish poop, and has to be algae.

Does anyone know what it is, if it is good or bad, and whether I should leave it or get rid of it? And if so how to get rid of it.

 

[Uberhoust]

It is cyanobacteria. I am fighting some now myself as are a number of other people on the forum. Typically it starts with high light, and high nutrient load of some sort, but as you read other accounts you will find that is not the whole story. There are two main immediate treatments and neither is ideal, you also have to try and find the underlying cause and that isn't that easy.

For the immediate you can either black out the tank for a few days, I used 5 days the last time. Or you can use a product like Blue Green Stain Remover, which rumor has it is an antibiotic, which some people feel we shouldn't use in an aquarium. Either route will get rid of the bacteria in the short term. I have used both but I prefer the blackout, I fear the Blue Green Stain remover might affect the bacteria we harbor in the filter and I don't like throwing antibiotics around. Some people also use Hydrogen Peroxide, hydrogen peroxide did not work well for me.

Once removed if you don't fix the cause, it will be back again. Lighting is a big deal, if you have too much light in the tank it can start again. Your lights should be on a timer anyways so try reducing the time the lights are on, I have gone from 13 hours once to closer to 9 hours now. The other issue is the nutrient load, reduce your feedings (keeping the fish feed) and do more water changes can help with the issue. That said it can have other unknown causes, in my case I am looking at changing the substrate because that is really the only difference between two of my tanks, one with cyanobacteria one without, is the substrate. Some people also mention that nerite snails help with it but that hasn't been my experience.

Note when you clean the tank try to remove as much as possible. Also the bacteria is very mobile, it can move to a better location if need be.

 

[FishyJoe]

It is cyanobacteria. I am fighting some now myself as are a number of other people on the forum. Typically it starts with high light, and high nutrient load of some sort, but as you read other accounts you will find that is not the whole story. There are two main immediate treatments and neither is ideal, you also have to try and find the underlying cause and that isn't that easy.

For the immediate you can either black out the tank for a few days, I used 5 days the last time. Or you can use a product like Blue Green Stain Remover, which rumor has it is an antibiotic, which some people feel we shouldn't use in an aquarium. Either route will get rid of the bacteria in the short term. I have used both but I prefer the blackout, I fear the Blue Green Stain remover might affect the bacteria we harbor in the filter and I don't like throwing antibiotics around. Some people also use Hydrogen Peroxide, hydrogen peroxide did not work well for me.

Once removed if you don't fix the cause, it will be back again. Lighting is a big deal, if you have too much light in the tank it can start again. Your lights should be on a timer anyways so try reducing the time the lights are on, I have gone from 13 hours once to closer to 9 hours now. The other issue is the nutrient load, reduce your feedings (keeping the fish feed) and do more water changes can help with the issue. That said it can have other unknown causes, in my case I am looking at changing the substrate because that is really the only difference between two of my tanks, one with cyanobacteria one without, is the substrate. Some people also mention that nerite snails help with it but that hasn't been my experience.

Note when you clean the tank try to remove as much as possible. Also the bacteria is very mobile, it can move to a better location if need be.

My tank is blacked out in the back and on two sides. Only the top and the front get light. I keep the blinds in the room closed but the tank light is probably on longer than it should be - which I can change now. So when I black out totally, does that also mean the top, as well as keeping the light off?

 

[Uberhoust]

I have only done the blackout once. I used black foam board over every surface including the top, (8 pieces for $1.00 each at a dollar store). I just used a nylon strap to hold the side pieces on, it took less than 20 minutes to setup.

A little light might have leaked in, ie not cave dark, but pretty close. After 5 days all the cyanobacteria was gone. It did affect my other plants but not drastically. The bacteria was gone for 3 months. When blacked out I feed the fish about half their normal amount and provided some ambient light while feeding. I typically try to only feed them what they can eat in 30 seconds to 1 minute, but I gave them even less during this period.