Macro in Sump - How Much Flow is Needed?

[Sdoutreefer]

I'm wanting to set up a little refugium with some LR rubble and macroalgae BUT my sump is relatively small and has pretty low flow. Do macroalgaes prefer the low flow? Or does it need a little movement? 13 years ago the hot macro was Chaeto and a lot of people were either recommending a "swirling" flow to keep the ball moving, while others recommended zero flow.

I know the hobby has really changed in the span of 13 years, so which one is it? Is a decent flow required for macro algaes? Or do they prefer low and slow?

 

[mann1139]

I think the worry is too much flow versus not enough.

If the sump has flow through it to the return pump, that should be fine.

 

[Sdoutreefer]

I think the worry is too much flow versus not enough.

If the sump has flow through it to the return pump, that should be fine.

That is the concern. Appologies it wasn’t clear.

Ok - thank your for the feedback!

 

[exnisstech]

Low flow, high flow, chaeto never seems to care IME. I've had it live for weeks with no flow or light and no water when I forgot to dump it after harvesting some.

 

[PotatoPig]

I have pretty low flow through mine and the chaeto does fine. If anything the low flow seems to let it just spread out rather than bunch up.

I got this chaeto as a 1” long single strand that came with other macro algae and now it fills the refugium portion of the sump.

Math time:

Based on the pump flow vs head chart there’s around 250gph going through a 20g sump - so about 33.5cu.ft/hour. The cross section of the refugium portion is about 1 square foot, so flow speed is 33.5/3600 x 12 = ~0.1 inch/second…