# Sand Turning blue?



## HZO (Jun 3, 2015)

The sand in my two week old dirted tank is turning blue. I am wondering if this is potentially harmful and if this any way to prevent it. Thanks.


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## nayr (Jan 18, 2014)

you got Cyanobacteria, aka BGA.. its caused by not enough Nitrogen. 

Are you fertilizing Macro (NPK) Nutrients?


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## baumer1781 (Feb 1, 2011)

You might be running the lights a bit long as well. Usually I get this when sunshine hits the side of the tank causing too much light along the substrate and it creeps up. Remove as much as you can asap and hit the spots along the sides with 3% H2O2 with the filter and pumps off. Wait a few minutes for the bubble show and it should be killed off, then run the pumps again. 

From the looks of it you've got a big outbreak which could be hard to recover from. BGA = blue-green algae btw which it is known by, but is a photosynthetic bacteria. Because of this there are options for antibiotic treatments and other whole tank dosing options, but I haven't used these. Keep an eye out for it and stop it before it spreads.


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## HZO (Jun 3, 2015)

nayr, I am not using any sort of fertilizer, and it is only (temporarily) stocked with 20 or so feeder Danios. I was under the impression that soil produced large amounts of nitrogen. 

baumer, I am a more than a bit confused. By photosynthetic, I take it that BGA can't grow without light, but it's under the sand, even in the middle of the tank. (The BGA in the second pic is only on the surface because I stirred the sand a bit.) Would "removing as much as I can" involve changing substrate? And would killing it with H2O2 require emptying the tank?


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## nayr (Jan 18, 2014)

I bet if you test your water parameters your Nitrates are at 0ppm, your water column also needs nutrients... 10-20ppm is what your shooting for in a planted tank.

my betta tank has Osmocote+ root tablets, tons of plants and light.. so many plants that I have to constantly add nitrates or else I get BGA.. 

Kill all your lights and add some nitrogen to the water until it starts to recede.


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## CanadianNerd (Jun 10, 2015)

I have the same thing in my tank (It also has sand) refer to 
http://www.plantedtank.net/forums/showthread.php?t=477617


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## shambhalove. (Jan 22, 2013)

Reduce light, start fertilizing, increase flow and you can spot dose it with a syringe of peroxide. It should be easy it deal with if it hasn't started forming sheets. 

Stirring the sand up a bit with a chop stick can help too, you dont wanna disturb the soil and mix the layers too much so a light stir on the top layer will help.


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## Beefy (Mar 6, 2015)

Erythromycin is very effective and will specifically target BGA without harming your biofilter or plants. Easily the best way to treat the symptoms while you work out the root cause of the problem.


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