Black algae on live rock

[InTheDark]

Hey guys,
I am fighting a problem with black algae on my live rock. My phosphates were too high and I am in the process of getting that under control. What can be done about black algae on live rock? Will it begin to clear up once the phosphates are back to normal?
Thanks

[7digits]

I think it's cyanobacteria. Try doing a large water change and siphoning as much as you can out.

[InTheDark]

Thanks 7digits,
I did a 30% water change yesterday to help with the high phosphates. The black algae was growing in mats and was stringy. I siphoned out as much as possible and right now the only visible black algae is on some of the live rock. I have some snails and a sea hare to help clean. It is really attached to the live rock well. I am wondering if I should to throw out the infected live rock, so it doesn't continue to spread, or will it disappear over time with normal level phosphates?

[leebca]

In general, we don't have anything in the hobby known as 'black algae.' So understanding exactly what it is you have is our first goal here.

Can you provide photos? I need clear photos of what it is you're looking at. Not only near photos, but close ups with good clarity.

Sometimes the thing we call red algae is so thick and so dark it is very dark red -- almost black -- but really dark red. It forms in mats. But I note you describe yours as stringy and mats. The mats of red algae can turn stringy when disturbed.

Just briefly -- red algae will 'go away' when it is under conditions it doesn't like. One of things it doesn't like is water circulation. You would need to increase your water circulation, leaving no corner or place without flowing water around and on it to cut back its growth AFTER it is physically removed.

Red algae generally likes poor water quality -- including organics and the phosphates you mentioned. So improving water quality will keep it under control. Do you use a skimmer? What is the size of your tank? Do you use a chemical filter (e.g., activated carbon)? These things help control organics.

Other than the above, I can't help much without knowing what it is you actually have.

Lastly, I would advise getting rid of the sea hare. They release toxins into the water and if one should die (which they do very easily), could wipe out the tank. Not worth the risk. Stick to snails.

;)

[InTheDark]

Thanks for all the advice leebca.

I will try to get some pictures tonight. Unfortunately I siphoned it off the sand and glass where it was matted and stringy so I won't be able to get a picture of the thick matting and stringy algae. Hopefully I can get a good photo of it on the live rock where it is not thick... it just seems to discolor it a bit. I may not be calling the proper name but it looks like algae and appears black under the lights (4- 65 watt bulbs) and against the white sand. It was only stringy where it was thickly matted so perhaps it is this dark red algae. I'll take a closer look to see if it is dark red.

In the meantime I have an 80 gallon tank with a surface skimmer and a protein skimmer and a single powerhead. I was given the tank by a friend and there appears to be 2 bags of carbon mixed with the bio balls. Perhaps I should replace the carbon? I also have about 60 pounds of live rock. About 3-4 pieces of live rock seem to have the algae. I will check the circulation in that area too.

Thanks for the tip on the Sea Hare. Do they release toxins while alive or just when they die? Either way I will get rid of him.

[leebca]

You should read this post, even though you have a system in operation. This post gives some good guidance on running a system: Setting Up a FOWLR Aquarium

Carbon should be half changed, about every 2 to 3 weeks. Just just change half of it for now; the other half in 2 weeks, then thereafter, one half every 2 to 3 weeks.

The single powerhead isn't enough. Inside the tank you need/want about 10x turnovers per hour. So all your pump ACTUAL pump rates should total about 800 gallons per hour or more (not too much more). This shortage would explain the presence of red algae.

Sea Hares will release a little toxin if it is threatened. But when they die, it is a massive release that can and has wiped out entire tanks. A nice idea and a neat creature but alas, not for the home aquarium.

[InTheDark]

I am using a Koralia #3 powerhead which advertises 850 GPH. I don't know what the actual GPH is for this pump. Is there a chart somewhere that shows actual flow rates for various pumps? Any recommendations on my 2nd pump? Koralia #1 (400 GPH)?

I read your "Setting up a FOWLR Aquarium" article. Very informative. I see I need to make some changes. Glad I found this website!

[leebca]

Pumps are rated without any back pressure (in general). There are usually charts for the pump which show head pressure in feet and the flow at a given back pressure. Then you calculate the back pressure in feet.

An elbow in-line is equal to 1 foot back pressure; every 10 feet length of tube is 1 foot back pressure; every foot rise is equal to 1 foot in back pressure; etc. Once you have the total feet in back pressure, then you read on the chart the actual pump rate in gph.

With regards to a powerhead, all of its rated flow should be there since resistance should be nearly none. However, these tend to deliver flow in a narrow area and don't (of course) push water under them. Thus two or more are needed at the least. Multiple slower flow-rated powerheads are better than one large one. When waste solids (a bit of food) doesn't settle but floats around, can't find a dead spot to settle, and gets to the overflow or mechanical filter, then the circulation is pretty good.

The water coming into the display from an outside pump (like a return pump on a refugium and/or sump setup) needs to be distributed to help eliminate dead spots too. If flow isn't preventing ALL dead spots, then you may need additional powerheads aimed at specific areas to remove dead spots.

This is a thread you should read, too: Red algae help please

[InTheDark]

I took a closer look at the algae using a flashlight and I can see that it is a very dark red. Unfortunately, I could not get my camera to focus on the algae within the tank so I was not able to get decent pictures of it. I'll try all your suggestions and see how it goes.

Thanks again for all the help!

[InTheDark]

I also took apart and cleaned the protein skimmer too. It seems the air intake was closed too much and it wasn't skimming hardly anything. It seems to be working very well now. Perhaps that, among other things, was contributing to my high phosphates.

[leebca]

The protein skimmer does not remove phosphates. It will remove phosphates connected to organics, but those are in a minority. The phosphates we worry mostly about are those dissolved in the water, which the skimmer doesn't affect/remove.

Be sure to read through the thread link provided above.