One of my friends got rid of his aquarium fish a while back, and he gave me his 15 gallon Aqua Tech aquarium pump and his 15 gallon Aqua Tech aquarium filter. I bought a dozen large shiners this morning, got them home, and there were 17 of them anywhere from 4" to 6". They're in an 18 gallon Sterlite plastic tub in about 14 gallons of water. I'm running the aquarium pump, it seems to be working fine. I haven't hooked up the Aqua Tech aquarium pump filter yet, but if I run the filter, is that sufficient circulation to where I really need the pump? And how many shiners do you think I can keep alive with this setup? Am I stretching my limits right now?