Regarding sand being sucked up into intakes of AquaClears or canister filters, I use an AquaClear filter sponge slipped over the intake, a slit in the top of the sponge allows you to slip it on and it will not slip off by accident. At each partial water change, slip it off, rinse in a bucket of water you just took out of the aquarium, and then slip the sponge back onto the intake

This also increases the time between canister filter cleanings ... yes !