recirculating pump size

[el chupanebre]

Is there a calculation to get the correct pump size for your particular setup? I am making a hydro setup for a SOG with 70 stations.

Rhizome's calculation for fan size in Noob's Growroom Setup really helped me when I was picking out my fan and could use some help with my pumps.

Also...is an airstone needed with an nft system with pump on 24/7?

[el chupanebre]

Side note: If this topic has been posted elsewhere or if anyone knows where I can find more information on this topic it would be greatly appreciated. Any reply is awesome. I'm curious and have had no luck finding this bit of information.

[herbie the love bud]

I think its been discussed a lot on gardenweb.com. Google on "head height" or lift. GPH. Over there I had seen some engineers helping answer the conversion questions.