Sand Changing Colour... Help!

[superman1]

Hello

ok so i was doing a clean of my tank and i decided to move it around. i lifted my bogwood up which has been in the same place as it has since the tank has been set up... but all the sand which was underneathe has turned grey. so i also moved some stones around and alot of the sand below the surface has turned grey.

what is this and how harful is it... i tried to vacumm it up but didnt really work. so i carried on with the clean up and tried to turn the sand around thinking it might be trapped gasses turning sour or something .. but when i checked on the tank today the sand has returned to its normal colour...

anyone experienced this before...

 

[RedeyesUK]

Yeah, you were right with your thinking... it goes that way from trapped gasses. Whether or not it's harmful is open to debate, but I've never had a problem with it.

To stop it recurring, make sure you lift your decorations etc and give the sand a stir with a stick every now and then.

 

[superman1]

ok thanks.. i thought having the cories was good enough as they turn the tank over but with about 4 cms of sand... dont think they will be doing that.. lol

 

[TylerFerretLord]

If you're worried about substrate gasses(no reason to, however), get some trumpet snails. They keep it nice and clean as they dig around.

Without actually seeing the sand first person, my guess would be that's it's just detritus that was trapped under the wood.