I'd agree that larger is better. The 210 is a 21" diameter filter, significantly less than 30". The Hayward website says it's good for 44 Gallon/Minute or 21K in 8 hours. That's probably overly optimistic, Larger filter = larger filter surface = slower velocity through the surface = better filtration. It'll probably work but you may need longer run times and might end up with lower water quality. Just my two cents.