I found this old thread and wanted to double check for current opinions.
I am doing the same thing, plumbing a sump overflow, and in the past I've let the finished product sit for a while (24 hours) before connecting it up.
The link towards the bottom of the thread above (from a plumber's site, it looks like) says that 1 hour of curing time it all that is required before the joint will be cure for low pressure use. That is all good, but my concern is related to the toxicity of the cement compound in a saltwater environment at 1 hour after application.
Is it really safe to start running your tank water through after just 1 hour of cure time?
Will any toxins be released into the system after a minimum wait time?
I'm thinking that just to be safe, I should probably wait at least 4 or 6 hours and make sure I flush it well with tap water, but has anyone done it after 1 hour on a reef system?