Good old calcium chloride, the stuff you add to your tank to raise calcium, is added to cement to make it cure faster.

Rona carries the white cement I used to make my rocks. If your ever out in the Walnut Grove area you can have the rest of the bag that's taking up space in my garage. I'm never going to use it.

Rob

there is another thread on this topic and IMO the rock made with softning salt looks way better. dont bother with the rock salt.

The other thing I considered making some rock out of ... was colored, sanded grout .. It comes in almost any color you want .. so why not have purple base rock? :) Though I imagine they would have to be 'ph cured' for a long time

cool thanks guys. always dependable. Ill go buy some type 10 tomorrow and get down to makin the rocks on tuesday (or the next sunny day). thanks for the offer spoot, but i think ill just buy the water softener salt when i go get the cement.

I am goign to be making up a batch of DIY rocks soon and I am wondering why Oyster Shells? Is it just for the texture or does it help by adding calciuim?

By the way Buckerfields right off #1 Hwy in Abbotsford has crushed oyster shells in Bulk.

This is a piece of homemade rock, that Mike did a few years ago. Cant tell it form the other now, except for the different look from its materials. Its supporting a main portion of my reef.

I can take a better pic if you wish. Attachment 2839

Type gu (general use) type 10 portland cement. I build ponds for a living and have had much sucess with this. Doesnt affect fish.
P.S cement takes 28 days to cure DO NOT PUT IN TANK UNCURED when cement cure it releases off gases. Good Luck

Oyster shells are just to add texture. I used aquarium gravel in mine, but I think oyster shells would give a coarser look.

thanks guys. i endeed up getting the specialty white portland type 10 cement. little bit expensive but I think it will blend in better in the tank than gray cement. A small batch has been curing for a week or so now. I think i might crack one open later to see how it went.

How did the aquarium gravel work? I have some kicking around and was considering a DIY batch.
Kevin