# Blackout time - Questions



## webcricket (Oct 16, 2006)

I have a nice infestation of hair algae starting to take hold in my low-light tank. While it's really very pretty green shimmering stuff, it's not acceptable. Excel doesn't seem to be touching it, though it took care of my little bits of BBA with no problem. I believe my next resort is a blackout. This being my first blackout, I have some questions:

How long should I black out the tank? 3 days? 4 days? All my plants are pretty hardy.

Should I dose normal fertilizers during the blackout (Seachem's N, P, K and Flourish)? I just got over a BGA and green spot infestation, I don't want them back.

Should I keep adding Excel during the blackout?

Will adding an airstone hurt anything? I have very little surface agitation and my fish would probably appreciate it.

I assume I will do a water change before and then again right after the blackout, correct?


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## MatPat (Mar 22, 2004)

To my knowledge, a blackout won't do much for your hair algae. Blackouts are usuallly best for Green Water and BGA. They may also give good results for GDA but I have not tried that yet.

A typical blackout is done for three days. I like to do a wtaer change both before and after. I top off the ferts prior to the blackout, tape black plastic to the tank and cover it with a heavy blanket. Turn off the CO2 and of course the lights  

Since the lights will not be on, you will not need to add ferts daily or every other day. No need to feed the fish either, they will be fine assuming they are healthy and have been fed well prior to the blackout. Just cover the tank and leave it alone for three days. An airstone probably won't hurt expecially if you have very little surface agitation.


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## webcricket (Oct 16, 2006)

Well, I'm assuming it's some type of hair/thread algae -










Had that pic posted in another thread but got no real ID on it. It's a super fine green algae, non-branching, grows quite long, easily pulls off of the plants, and grows a bit on the tank glass as well. I did manually wipe a mess of it off my java fern, but it's come back after about a week and is popping up on other plants now. It's not a stiff algae, it moves and shimmers in the water current.


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## hoppycalif (Apr 7, 2005)

Most of us run into algae problems when we have a lot of light on the tank. Or, whatever algae problems we do have get worse when we increase the light. And, we know, I think, that all algae we see needs light to prosper. So, doesn't it make sense that a blackout would be effective against all kinds of algae? Possibly some algae could just rest in the dark, awaiting the return of the light. That part I don't know about.


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## MatPat (Mar 22, 2004)

Hoppy, you are right, a blackout would be effective against this algae sooner or later but I think the plants would be gone before the algae would. I have no proof of this, just a feeling 

I suppose it would be worth a try for webcricket to give a 3-4 day blackout a try. Four days shouldn't hurt the plants/fish and we can see if it will have any effect on the algae. We could get a nice suprise out of it!


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## webcricket (Oct 16, 2006)

Well now I'm having second thoughts, LOL. 

I do know hair algae is a tough one - I fought with clado algae once before in a non-planted tank and I swear I heard it laughing when I tried depriving the tank of light. I suppose for now I will up the Excel to 2x the "after water change" dose and see if that touches this stuff. I hadn't gone higher since the regular dosing of it took care of the BBA and I figured it should get the hair as well.

Do you think H2O2 treatment of the tank might be useful here if the Excel fails?


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## IUnknown (Feb 24, 2004)

What about oxygen levels? Will covering my tank with black plastic kill my fish?


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## hoppycalif (Apr 7, 2005)

I did a 3 day blackout trying to kill off GDA for good, and it didn't seem to bother either the fish or the plants. One thing I learned though is, if you have a wood hood on the tank, it will warp from the trapped moisture if you include the hood under the wrappings. Mine straightened out when I went back to having the lights on and the ventilating fan operating, but the warpage was pretty bad before. I didn't dose anything during my blackout, no fertilizers, no CO2, no Excel, and no fish food.


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## IUnknown (Feb 24, 2004)

Well, I lost most of my cherry shrimp. How depressing. I think I screwed up by adding excel during the black out. I think they died from lack of oxygen, but I still need to research how excel effects shrimp.


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## IUnknown (Feb 24, 2004)

So looks like people don't have problems with excel and their shrimp. I did read that excel uses up oxygen in the tank, so that must have been what did it.


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## Zapins (Jul 28, 2004)

IUunknown I did the same thing. Blacked out for 3 days w/ excel, my fish and HC died.

Not sure if it was the lack of O2 or the excel that did it. Probably O2.


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