Discolored sand

[Morganna]

Hello!
I wasn't sure where to put this question, so mods, feel free to move it to a better place.
I just removed some wood from my tank in order to scrub off some excess algae and fungus stuff. But when removed, I see that anywhere that the wood was in contact with the sand, the sand is now a weird gray, where before it was tan. Picture attached. Any info on what is happening and what I need to do about it is greatly appreciated. Sorry for the bad pic, was best I could manage.
-Morganna

 

[Rocky998]

Just like in nature, when a place is covered it may be discolored.
It could be that the wood slowly "transferred" it's color to the sand OR that was the sand's color when it was originally put in and all the other sand is actually discolored because it was exposed.

But in either case I don't think I would be too concerned. Out of caution, the only thing I would do is a medium depth vacuum for that area because there is always bacteria everywhere and sometimes the bad stuff can be under things such as wood, rocks, and other pieces of decor.

I'm sure others with more experience can shine in some more light on the subject and if I'm wrong on anything they can correct me.

 

[Colin_T]

The black coloured sand is anaerobic and is caused by rotting matter and lack of oxygenated water in and around that sand.

If you gravel clean the sand regularly you shouldn't have anymore problems like that.

 

[Byron]

Moving wood is dangerous, unless it is regularly done. And when you do, always have the water changer in hand to deal with the area under the wood.

The anaerobic build-up is normal, and never an issue until you move the wood (or rock, etc), then it can kill fish rapidly depending upon the extent. I never touched solid wood or rock in my tanks, for years. But when I did for some reason, I vacuumed every tidbit of sand and organics that I cold, and never lost a fish. Wasn't done very often, there is no need, as these anaerobic areas are part of a healthy aquarium--provided they are not tdisturbed.

 

[Rocky998]

The black coloured sand is anaerobic and is caused by rotting matter and lack of oxygenated water in and around that sand.

If you gravel clean the sand regularly you shouldn't have anymore problems like that.

That's the word I was looking for! Anaerobic!

 

[Morganna]

Everything noted!
@Byron, thankfully there are no inhabitants in the tank, and so nothing harmed. I hope to get some shrimp in there soon, and they would keep the wood clean, and thus then no reason for me to take it out. But I will be wary of moving in the future, so thank you for warning me.
@Colin_T, thank you for the advice on how to clean it.

 

[Deleted member 149562]

Get a big turkey baster from a supermarket, use it to suck up the muck and then puff the sand where its compacted by filling the baster with water from the aquarium and stabbing it under the sand and puffing it...once puffed you can grab detritus in the baster and flush it

A turkey baster has a million uses and very few of them involve a turkey