A friend of mine is starting a 55 gallon African Cichlid tank. He wants to use sand as the substrate. Is it best to put the sand in before the water or does it not matter?
It doesn't really matter but putting the sand in first will cause a lot less clouding. Just make sure after he puts the sand/water in to wait a bit for it all to settle before turning his filter on.
Having the sand in prior is ideal. If you add the sand after make sure to turn off any mech filters, so the impellers don't get shot by picking up sand. Removing the intakes from the tank is safer if you have a canister.