Blackout - Tropical Fish Keeping - Aquarium fish care and resources
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post #1 of 23 Old 01-18-2010, 12:00 PM Thread Starter
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Post Blackout

Some of you may remember the headaches I have been having with cyanobacteria (a.k.a. BGA) in my 32g ( I have been waiting for the appropriate time to do a total 3 day blackout of my tank to try and get rid of it... and today is it! This thread may come in handy for others who may have to go down that route eventually so here's a day-by-day account of the event...

Day 1:

My tank is in a very day corner of the house and if I don't turn the lights on, it will remain in total darkness all day long. Problem is, it is in y office and I work from home... so I need some light for myself. This morning I opened the door to my office and turned off the switch to the tank lights before the timer turned them on automatically. I then threw a think blanket over the tank and strapped in with a moving strap. It's weird to look at the tank with a blanket over it and something that almost looks like a chain and lock over it... I fed the fishies twice yesterday: at this rate they are not going to get any food until Thursday morning.

The hardest part is not to peek...
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post #2 of 23 Old 01-18-2010, 02:41 PM
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I just wanted to mention that if cyanobacteria is what you are really dealing with, the blackout method may not work so well. The reason for this is because cyanobacteria feeds primarily from organic matter found in the tank. If the level of organics is not relieved, the cyanobacteria will likely come back or not die out at all during the period of blackout.
Blackouts tend to work only for those tanks who's issue is caused by a photosynthetic species of algae, which true cyanobacteria is not... it is a bacteria just as the name implies.

Good Luck with your tank.

Dawn Moneyhan
Aquatics Specialist/Nutritionist
Juneau, WI
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post #3 of 23 Old 01-18-2010, 02:55 PM
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hope all goes well my friend keep us posted.....

Jumping Back into the Freshwater!!!
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post #4 of 23 Old 01-18-2010, 04:22 PM
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Apart from what we already discussed via PM; I just wanted to add...

I had cyanobacteri, actually a very nasty wide spread case and a 3 day black out followed by a gravel vac (cause it all turned into what looked like dust bunnies) cleared mine for good and been gone ever since then.

~ Life Is Too Short, Break The Rules, Forgive Quickly, Kiss Slowly, Love Truly, Laugh Uncontrollably And Never Regret Anything that Made You Smile.
Life May Not Be The Party We Hoped For, But While We're Here, We Should Dance. ~
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post #5 of 23 Old 01-18-2010, 11:19 PM
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Originally Posted by bettababy View Post
The reason for this is because cyanobacteria feeds primarily from organic matter found in the tank...Blackouts tend to work only for those tanks who's issue is caused by a photosynthetic species of algae, which true cyanobacteria is not... it is a bacteria just as the name implies.
Cyanobacteria are photosynthetic.

Life History and Ecology of Cyanobacteria

Heterocystic cyanobacteria cells can metabolize nitrogen but only under anoxic conditions (i.e. ones that wouldn't occur on the surfaces inside your fish tank, where the cyanobacteria in question are growing). Depending on the species, the cyanobacteria that commonly grows in our tanks may not even be able to grow heterocysts and may exist entirely in an aerobic, photosynthetic state.

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post #6 of 23 Old 01-19-2010, 10:30 AM Thread Starter
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Day 2:

Well I'm afraid I didn't really think about my stuff before I started this thread: I wanted to share the experience with everyone so that if anyone ever needed to perform a blackout then this info may be readily available. And this will still work... but here I am on day 2 and really... the tank's been in a blackout for 24 hours! Tada!

I can't see the tank, I can't see the fish, I can't see the plants, I can't see anything! I have to put my ear to the blanket to figure out if the filter is still going! And it's not even really a nice blanket to look at. I'm dying to take a peek...

My issues with Cyanobacteria (a.k.a. BGA):
I am hearing a great many things about Cyanobacteria. How to prevent it, how to remove it, etc. Everything I read has a different suggestion to try to get rid of it. And very few of the stories I read actually are backed up with a successful outcome. There's a lot of "this is what you should do" and very little of "this is what worked". The truth of the matter is I have been somewhat successful in controlling my Cyanobacteria problem by manually removing it from the surfaces where it lived but no matter what I do, it simply keeps coming back. I want to get rid of it for good, and I want to do it without using chems. Hence the blackout...

So I wait...
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post #7 of 23 Old 01-19-2010, 11:35 AM
I hope everything works out well for you. Good luck!

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post #8 of 23 Old 01-19-2010, 01:52 PM
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You asked for those with experience at what works to comment, so here you are.

I have seen cyanobacteria rarely over 20 years, usually as a single strand or two on a floating plant, and once removed that's it. But last autumn I suddenly had a major infestation in my 70g SE Asian aquarium, which I have (apparently) eliminated.

It appeared on the floating plants, and covered the surface within a few days. During the weekly pwc I removed as much as I could with my fingers. Within 2-3 days I could clearly see it returning, and the following week it was a thick as before. Same treatment. I also stopped liquid fertilizer for 2 weeks. I made no change to the lights. After about 2 months of this, I had removed it one week as usual, and by the following week none had re-appeared. Two weeks later, I saw a very small patch on one floating plant, removed it, and now 3 weeks later still no sign of it.

Karen Randall (I think it was) once wrote that it seems to occur more in tanks with Cryptocoryne plants; I have a small group in this tank. I also knew from the time I set this tank up in early August last year (2009) that it was not biologically balanced. I planted the tank full of Hygrophila difformis (30 stems), 3 Aponogeton, the crypts from an existing tank, and floating Ceratopteris. Temperature is warmer than my other tanks, around 80F, due to the Chocolate gourami [two species, which regularly spawn by the way] and pygmy sparkling gourami. I am waiting to get some red tiger lotus and will then properly aquascape this tank, so fast-growing stem plants were pushed in and left. Twice weekly liquid fertilizer was added, and of course the regular weekly pwc of 50-60%.

Cyanobacteria, unlike most bacteria, photosynthesize like all plants (which includes algae), and thus it requires light. It also has the unique ability (not shared by any plants) of assimilating nitrogen in its pure form; plants must assimilate nitrogen as ammonium or nitrate. Cyanobacteria therefore requires nutrients in the presence of light.

Many methods to eradicate cyanobacteria have been suggested, and all of them seem to work at least in some cases. Increasing nutrients is one, and at first this seems incongruous; but in planted aquaria it has been shown that the plants will use the nutrients and the cyanobacteria will diminish. It may be no coincidence that my cyanobacteria died off when I increased the liquid fertilization; I had ceased this, but the week prior to the first sign of no cyanobacteria, I began using liquid fertilizer once after the pwc.

Blackouts have also been recommended, but these must be carefully monitored. The dying bacteria will pollute the tank. And if the infestation is heavy and it suddenly dies off, the effect could be catastrophic. Other bacteria will multiply, oxygen is rapidly used, plants die off and fish are harmed or worse. Rhonda Wilson, noted plant authority and regular columnist for TFH, recommends daily significant partial water changes during blackouts, with thorough vacuuming of the substrate to remove the dead bacteria. Ensure there is adequate filtration. Many aquarists report that the cyanobacteria returns after the blackout treatment. I suspect this is in line with Dawn's comments, with which I completely agree, that organics are the issue. I mentioned above the unsettled biological equilibrium in my 70g.

Paul Krombholz of Tougaloo College in Mississippi has written of specific aquatic plants that secrete chemicals that will inhibit cyanobacteria and certain algae, and Diana Walstad has written the same. This is called allelopathy, but that is a whole new topic.


Byron Hosking, BMus, MA
Vancouver, BC, Canada

The aquarist is one who must learn the ways of the biologist, the chemist, and the veterinarian. [unknown source]

Something we all need to remember: The fish you've acquired was quite happy not being owned by you, minding its own business. If you’re going to take it under your wing then you’re responsible for it. Every aspect of its life is under your control, from water quality and temperature to swimming space. [Nathan Hill in PFK]

Last edited by Byron; 01-19-2010 at 02:33 PM.
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post #9 of 23 Old 01-19-2010, 02:03 PM
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I can offer you "this is what worked for me" stories if that is what you desire, but in each situation it was organic based. It was always a matter of removing the excess organics that the bacteria were feeding on.

Probably my biggest challenge in battling cyanobacteria was in my dwarf puffer tank. The cause was the food, which as you can imagine, was difficult to control. These puffers ate only live snails. After studying their eating habits endlessly, spending hours watching them eat every night, I figured it out. What turned out to be happening was the way they ate the snails was to take a bite or 2 out of the foot of the snail and then move on. This, of course, was usually enough to kill the snail, but the snail pulled up into the shell where the fish couldn't reach it anymore... thus it died and all of that organic pollution was in the tank.

Because these fish ate almost constantly with their foraging all day and night, and because they were getting so little actual food content from so many snails... I proceeded to deshell the snails. The fish refused to eat a dead snail, so I spent weeks learning to cut enough of the shell away to allow the fish full access to the snail body without killing the snail. Upon doing this the puffers were able to consume the entire snail, which limited the amount of organic waste in the tank. Within about 10 days the cyano bloom was gone and never came back. There was no black out, no extra water changes. Basically, I starved the cyano from its food supply.

Thus I stand on my statement of finding the cause of the bloom, because if you don't find what is causing it, it is surely going to return.

When battling bad cyano blooms in saltwater tanks it is always the same solution that works for me. Using airline tubing I vac the rock to remove the silt buildup in the pockets of the rock, thus freeing any organic build up trapped within and under the silt. The results are always the same... if the silt is kept under control the cyano does not return. No black outs have ever been needed (or worked) for me when battling that stuff... it was simply a matter of figuring out what is feeding it and eliminating its food source.

I hope this was more helpful to you.

Dawn Moneyhan
Aquatics Specialist/Nutritionist
Juneau, WI
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post #10 of 23 Old 01-19-2010, 03:31 PM
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you know my story in detail already so I won't repeat....I'm proud of you thou you managed 24hrs already without opening it up and checking everything

~ Life Is Too Short, Break The Rules, Forgive Quickly, Kiss Slowly, Love Truly, Laugh Uncontrollably And Never Regret Anything that Made You Smile.
Life May Not Be The Party We Hoped For, But While We're Here, We Should Dance. ~
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