Cement use in FOWLR tanks

[Borderjumper]

Originally Posted by Fishward

Anyone have experience using cement in a tank? I have heard they will cause chronically high pH? will this taper off over time?
I am trying to make a wall for the back of my 30Gal Hex and am contemplating using cement with embedded LR. (LR will die during construction i know)

thoughts?

I used white cement when I made my rock walls. I dont remember the brand but I could look tomorrow.

I mixed it roughly 1to4 with arganite sand. Poured it into the precut eggcrate form and let it set for a couple of days. Since the tank was empty I put it in where I wanted it and let the tank run for 6 weeks with fresh water ,changing the water as often as every day when I thought about it and every 3 days at the max.
Roughly 20 gallon tank with 2 walls (16x16) of the cement. The PH would go up within a couple of hours to 12-14! After 6 weeks it would hold pretty steady at 8 so I ran it for a couple more days with some vinegar added. After that I ran it with saltwater umm for a week or so adding vinegar.

Emptyed it out, refilled it and added some mushrooms and 2 small chromis.. then the algae started! It was a cesspool for at least a month.. then suddenly all the algae was gone and coraline was growing.

I have 2 deepwater anthias and a seahorse in that tank and havent had a bit of problem with ph.

If you want more details on how I poured the walls and formed them send me a PM.