# Blackout treatment for BGA



## John Schultz

I just tried a three-day blackout to rid my aquarium of a major BGA problem. When I uncovered the tank at the end of the third day, I found some of the shrimp had died and the fish were suffering oxygen deprivation as evidenced by surface gasping. Even the worms from the soil had crawled to the surface! Also, the water has become cloudy. It seems the BGA is dead, but the treatment appears to have been costly. I'd like to hear theories on the oxygen problem. My guess is that the absence of light, the plants absorbed the oxygen and the column ran out of O2. Anyone have a different view? Any other experiences with blackout treatments?

My tank is 56 gal (120L) six-month old, planted with Amazon Sword, Hydrocotyle Verticillata, Cryptocoryne Crispatula, and some others. CO2 injection at about 20ppm on timer with light (Metal Halide--Crystal Shine 150) . Substrate is ADA soil. Water: pH 6.2, kH about 20ppm, temp 24C. Fish and critters: 15 fat, mature neon tetras, two abenibafa (Japanese name--anyone know the English name?) and--now--about 10 yamato shrimp survivors. 

John Schultz


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## trenac

_Did you turn off the C02 & use an airstone during the blackout?_


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## hoppycalif

Any algae that died begins to decompose and that uses a lot of oxygen. Any blackout needs to be immediately followed with a major water change to get rid of the dead stuff. Also, when you blackout the tank, make sure there is still a good way for air to get to the water surface. That will help keep oxygen replenished.


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## John Schultz

The CO2 was off but I did not use an air stone. 
John


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## John Schultz

Thanks Hoppy. I was being careful--too careful--that light did not get to the tank.


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## Mr. Fish

As long as your filter is on is that not enough oxygen during a blackout ? You dont need an airstone to my understanding


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## lilypotter2009

An airstone is needed during blackout treatment.

Just before you do the black out, feed the fish all they can eat, then do a water change 50% or more, add the KN03, then cover the tank for 3 days, no peaking, no feeding, disconnect the DIY C02 during the blackout. you wont need it.

After the 3rd day, uncover the tank, do another water change, dose the tank, re-connect the C02 then stay on top of things.

A blackout will not harm the fish or shrimps. BGA can be a PITA, so you have to keep on top of it. I've done dozens of blackouts in the past, and I've never lost one fish or shrimp because of it.


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## Seattle_Aquarist

Hi John Schultz,

I recently got rid of the cyanobacteria (BGA) infestation I had in one of my aquariums for over six months. The tank has medium light, no CO2, weekly 33% water changes, and was dosed with ferts per the PPS-Pro method. I tried the Excel (Glutaraldehyde) 2X normal dosage treatment that has worked on other algae problems in the past without success. It was very frustrating, not only unsightly but the tank had a definite smell (musty/moldy) when I opened the lid.

A couple of months ago I came across a post on one of the planted tank forums indicating the BGA is caused by a nitrogen deficiency. I decided to try increasing my nitrogen. I started dosing KNO3 at the rate of 1/8 teaspoon per 10 gallons daily. All other factors remained the same including the 33% weekly water changes. After a few weeks I noticed that the new leaves on the plants were not being covered by the BGA. I continued the dosage and after another couple of weeks the new leaves remained BGA free. In addition the BGA on the older leaves seemed to diminish and the "smell" in the tank decreased.

As of last weekend it has been two months and I have not had any additional growth of BGA in my tank. The new leaves remain BGA free and the leaves that were affected have much less BGA on them. I removed the affected leaves leaving only the new leaves that are BGA free. The tank no longer has that moldy/musty smell but instead has that sweet/earthy smell my other tanks have. Nothing changed in the tank except the addition of KNO3 at the higher dosage.


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