Fluval FX5 gph question please help

[chefrific]

I'm in the market for a FX5, but I see conflicting stats on the gallons per hour. Some list it as 607gph and some say 925gph. That's a big difference. Does anyone know why? was there an older model that was slower?

 

[smpage]

the box will say 925 and the manual will say closer to 600. it just depends on how full of media you fill it.

 

[brianp]

My understanding is that the pump itself, detached from any other hardware has a rate of approx. 925 gph. Once the pump is attached to the canister with media baskets, foam and the accompanying hoses, the rate will drop to approx. 650 gph due to resistance encountered by the water as it moves through this system. Once you add media to the baskets, you can expect a further drop, the magnitude of which is highly user-specific and dependent upon the particular media which are added. The metric I use is that you should use one FX5 for every 120-150 gallons. I have two FX5s on a tank that has a working volume of approx. 320 gallons and they perform beautifully with only the white foam and Ehfisubstrat Pro.