Concrete to bond rock?
 

Has anyone here used concrete to bond rocks, as opposed to say building a PVC skeletal structure, or using acrylic or fibreglass rods after drilling holes?

Noticed Ching Chai's doing it on his new tank build so got to thinking about it. He says he's using regular concrete. I thought this would make the pH of the water unpalatable for quite some time?

Or is it OK in small enough doses?

I remember a few years ago about a polymer based concrete which I think is used as a patching compound, but I couldn't find the exact brand name (I think it was discontinued). And I kind of forget the name now anyhow. :redface:

I did find another polymer based patching compound though at Home Depot, but I'm not sure how strong it would be. Maybe it's OK?

Or is it really OK just to use regular old Portland cement and just use as little as possible? (Call me a skeptic, I just don't see me getting away with it, is all..)

I imagine that's a poor idea since it takes so long to cure. I'm pretty sure it affects more than just the pH. I do believe it leaches something for awhile, but I'm not totally sure. I wouldn't try it.

If you can get a hold of Thorite Cement (check with BASF (they are the big distributor) to find a local retailer).

This is a marine based cement and won't cause a pH change like normal cement. Google "Thorite Cement"..... there are many reef related threads about thorite.

Cheers,
Vic

Sanjay Joshi used it on his big build....... check out his thread:

http://reefcentral.com/forums/showth...&pagenumber=26

Cheers,
Vic

Thorite! That's the stuff I was thinking of. I thought I read it was discontinued, but I can't find any info now to confirm that. Maybe it's more that I have no idea where you can get it. HD/Rona/etc doesn't seem to have it.

This is BASF the main distributor of Thorite. Give them a try.
http://www.thoroproducts.com/

Charger Corp also distributes it
http://www.chargar.com/Products/prod_mf.html

Cheers,
Vic

IMO it would be perfectly fine to use relatively small amounts of portland cement. amount of cement relative to volume of water will determine how rapidly the cement will change the Ph, so it has to be considered on a case-by-case basis. You would just have to keep a closer eye on Ph for about a month than most people do on their tanks; I don't think it would be too hard to buffer or perform water changes to combat it.

But then we have read about some of the DIY rock, where the recipe was off a bit and it wiped out peeps tanks....

I have done this and IMO if you have the time to let the concrete cure and leach its high PH in RO water, its much better than PVC structures or zip ties. It ends up looking the most natural. Once the concrete grows over with coraline and whatnot, the rocks look like one big piece.

I think I used portland cement. Whatever it was, nothing fancy, cheap and never had problems. I had that tank up 3 years.

How long did you let it cure for Justin?

IMO the time for me to figure this out is now, when I have a stockpile of rock in a rubbermaid. It's wet but not otherwise hugely live as it's been sitting for a while. So I can fill my tank and let it cure in place before cycling but I wonder if I'd have to dump a bottle of bacteria in to reseed the rock and let it re-cycle before I transfer any livestock.

I'll try looking for the Thorite though too in the meantime.