Canister Filter as sump?

[pegrochilakila]

Im new on this hobby but i been running my tank with a canister and till this point no problems at all my tank is small 30 gl, 55 lb of LV 40 lb of aragonite sand mix soft reef and fish.- my filter is a fluval 305 with sponges and 3 lb of LR crumbles
and 2 bag with aragonite sand and little chunks of LR, seriously i been hearing a lot of bad things about canister that i get confused but i experience person in this hobby give this idea with the canister and he said just follow your heart