ATS sump flow?

[greaps]

How does one size an return pump when using a sump with ATS / refugium. I'm considering building a 40 gallon breeder into a sump for a 120 gallon RR tank. I understand the return pump is what limits how much water passes through a sump / filter, but when a vertical waterfall ATS is in operation, is it not the smaller pump powering the ATS that would be the limiting factor? Sort of like making sure enough water runs through a sump to maximize a protein skimmers capability. Therefore I would assume much lower GPH return pumps would work just as well unless I am missing something. For an ATS sump / no socks, no filter floss / no mechanical filtration, simply a ATS / refugium sump.

[SantaMonica]

Welcome,

The return pump really does not matter. A scrubber removes a very small amount of nutrients per minute, although it does it 24/7, so more turnover in the sump won't affect it.

The important part is enough flow on the scrubber.

[greaps]

Thank you, makes sense, I just wanted my understanding of it validated. Thank you SM.