calcium hydroxide need to be lab grade?

[orlenz]

I found a local place to buy calcium hydroxide, do I ned lab grade? or is the lower grade okay to use?

 

[Randy Holmes-Farley]

Food grade is fine. Technical and agricultural grades may not be. I discuss grades in this article:

What Your Grandmother Never Told You About Lime
http://reefkeeping.com/issues/2005-01/rhf/index.htm