You should be fine, just check the levels of his water and your water first. Temp is a big concern! Also check salinity levels. If you have to, drop down the larger volume's salinity to match the lesser. You do not want to raise the salinity quickly, but lowering it is ok. Check all of the params and make sure it is reef safe. You could wait a few days, but if everything is in order you should be alright. Seed your new sandbed with sand from your other tank(s)... oh yeah, be a little weary of putting the corals in too quickly!