Are concrete fixtures safe in a FW aquarium? :?:

[MrDaytona]

I am contemplating making a wall with various caves and thru tunnels to put inside my FW tank. I know there is lime in the concrete but once cured is it safe for the fish?

The dimensions would be 3' wide x 3' tall x 1 ' deep. I realize this will be quite a bit of weight, but I am hoping to make an eye pleasing display, and much of the weight would be lost by all the tunnels and caves.

Anyone with experience in concrete it would be appreciated if you replied.

Thanks. 8)

 

[Enki]

I don't have any direct experience but I have done a bit of research on the topic.

The key with concrete is to cure it in FW for at least a month, to leech out the majority of the free minerals. The thinner the walls the faster it will cure.

This article has a great plan for a background full of caves. I am thinking of making one of these for my 30. Looks pretty good, makes LOTS of caves without using much floorspace, or any concrete that needs to cure for months :

 

[ferret]

Yes, I love the above plan. I haven't gotten around to doing it yet, but fully plan to. I just haven't figured out yet how to work my filter intakes and heaters around it.

 

[jratuszn]

I've also heard of people coating the cured concrete in an epoxy/sand mixture to seal whatever may leach out of the concrete. Seems kinda risky, though.

-J