26 gallon tank 24x18x14. Single overflow to a under tank sump with two returns. I want to run a SCWD and then using loc line I'll split the return in to 4 total. I will also be using two koralia nanos for water flow. I am not trying to get a ton of flow from the sump, jut some alternating current. Would a Mag 3 be enough or should I jump to a Mag 5? I am not planning on keeping any high flow demanding corals either.