# Play sand - black spots



## freph (Apr 4, 2011)

The only "black spots" I had when I was using play sand was from darker, heavier particles that settled to the bottom. Currently, my pool filter sand does this as well (they're not anaerobic spots). Anaerobic spots generally have a smell to them, so I suspect darker particles settling is the case for you. However, I could be mistaken. Hopefully a more knowledgeable member can give some insight into the matter.


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## ThinkTank (May 24, 2011)

I suppose thats possible, but most of the spots seem more like a stain than an accumulation of debris. Maybe algae?


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## labgeek (May 16, 2011)

Sounds like stains caused by hydrogen sulfide reactions to me. Especially with 6 inches of substrate..

Is it decaying material or much more solid?


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## AoxomoxoA (Apr 22, 2010)

This happened to me also, looked like a stain. Mine started stinking about the same time things started dying. I'll never use playsand again, & recommend you change it.


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## Heartnet (Sep 13, 2009)

6" deep? I'm surprised your play sand doesn't have more anaerobic spots, since it seems you have some source of rotting organics. I've heard people who keep corydoras only tanks with 2+ inch of play sand develop killer anaerobic spots if not properly stirred on a routine basis. 

Play sand isn't necessarily bad depending on what you use it for. It only becomes bad when piled too deeply and isn't properly stirred by either you or your aquatic denizens coupled with a high organic content that increases the chance of it getting buried and going anaerobic.



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## ThinkTank (May 24, 2011)

I didn't realize piling it deep could cause problems. Are other substrates ok for making hills (gravel,soil)?

I bought this tank as an upgrade for my wifes goldfish. Its pretty much off limits except for planting. I get the evil eye anytime my arm goes in the tank -lol. So if I can avoid a major overhaul that would be best (but i'd love to use a potting soil/sand cap substrate).

I made a couple raised areas in the hopes that I could keep the crayfish contained to the lower area and plant the high parts....but between the cray and the goldfish, the plants get trashed so its a lost cause for the most part. 

There are dark areas under/around the rocks that appears to be mulm? But in the substrate itself it seems like the sand grains are stained. I took some out of the tank and it rubs/washes off easily. No smell at all.


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## Heartnet (Sep 13, 2009)

ThinkTank said:


> I didn't realize piling it deep could cause problems. Are other substrates ok for making hills (gravel,soil)?
> 
> I bought this tank as an upgrade for my wifes goldfish. Its pretty much off limits except for planting. I get the evil eye anytime my arm goes in the tank -lol. So if I can avoid a major overhaul that would be best (but i'd love to use a potting soil/sand cap substrate).
> 
> ...


Lol I can imagine me doing the same to someone messing with my tanks. 

I have no evidence to support what I'm saying, but this is just what I gathered from anecdotal evidence while reserching the use of play sand in my corydoras themed tank over at aquahobby. 

I don't think the issue is solely piling it too high; Its piling it too high combined with organics (like mulm) which can get buried in large enough amounts if not removed. So I would assume you can use anything you wanted to build hills. Just a matter of which one is easy to keep clean to discourage conditions leading up to anaerobic dvelopment. it so happens that sand would be a betted promoter of this than normal gravel since it can compact so easily.

Its really a trade off sometimes. Fish for the plants? Or plants for the fish? What's good for one might not be the best for the other.
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## IxIBluepitIxI (Jan 25, 2011)

I had this happen to me with my silica sand. This is what happened I had brown algae growing on top of the sand. I covered the algae topped sand with sand from the bottom of the aquarium bed after a couple of months I noted the sandwiched algae had turned black.
My blackish sand didn't have a smell either but I know it was the algae decaying.


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## echoofformless (Jan 1, 2008)

Why do I never seem to have problems with my fine sands? I've even had Repti-Sand (so fine it's practically mud) and never had an issue with anaerobia. I do keep trumpet snails in every tank, could that be what's saving me from this?


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