Adding baffles to sump
 

I will be adding some more baffles to my sump as the micro bubbles are getting into my main tank. Im using weld-on #3 and was wondering how long after glueing them can i put water back in the sump as it is already in use and has to be drained to do this.

Weld #3 is very thin and dries very quickly. Because your baffles won't be structural you should be able to fill the sump within an hour after gluing. If you want to wait until it's full cured then you will have to wait about 24 hours.