Sump Flow Rate

[Lampshade]

I've been wondering about everyone with slow sump rates. After looking around most people have stated that it's because the skimmer has to fully clear the water before it's moved. But I'm looking at it wondering why skimming to 0 organics is critical? Granted you want 0 organics in your system, but wouldn't feeding the skimmer with un skimmed water be most benificial? Water passing through the skimmer 2-3 times seems like a waste of skimmer time to me. Anyways, if there's other reasons I'd be more than happy to hear them. I agree that if you have a Skimmer->Fuge->Return then it should be slow for fuge flow. But if you run Skimmer->Return<-Fuge then it shouldn't matter should it?

Main reason for the question is that I'm setting up my new tank and have lots of play room on my return flow, and a 10x + turnover seems like it wouldn't be all that bad.

[lastlight]

I think people's rationale is this: if your skimmer can't process MORE than x gallons per hour why put more than that through a sump when it will just mean more headaches with microbubbles and noise.

I think internal skimmers aren't exactly rated with a flow requirement like external skimmers. Afterall the water is just flowing right by the skimmer and it just pulls from that stream so dirty water certainly does get past it.

I think most people don't want the noise/bubble issues associated with crazy flow thru a sump.

[sphelps]

For some reason people tend to think that the return pump flow rate should not be more than the skimmer flow rate because the overflow water will bypass the skimmer otherwise. While this may hold true in a skimmer that is actually plumbed inline with an overflow it is certainly not the case for the typical in sump skimmer. The skimmer flow rate is completely independent from the return flow rate and even if the flow rates are matched there is no guarantee that the skimmer will cycle 100% of overflow water. In order to actually make this happen you would have to design the sump so the skimmer has to move the water from one chamber to the next meaning the flow rates would have to be perfectly matched which is virtually impossible. The other problem with this common assumption is once the tank has reached equilibrium the sump is simply an extension of the display tank, people tend to think that the water in the overflow box has more nutrients than the rest of the tank and it’s important that those extra nutrients don’t get put back in the display. This is a false assumption, skimmers remove dissolved organics and the concentration of these organics will be constant throughout the tank.

In my mind a higher flow rate insures the skimmer chamber in the sump also has a good turnover which will insure it always brings in new water but realistically once equilibrium is met the return flow rate will have no real effect in skimming efficiency. When deciding on a return pump it’s best to consider things that actually matter such as sump and display size, if powerheads will be used, micro-bubbles from skimmer and overflow, noise and your overflow drain limitations.

[mark]

other than maybe the reasoning lower flow through the sump too have a small return pump, therefore less wattage, being greener, smaller environmental footprint (and then should be rethinking about having a tank in the first place), can't buy into the rest of the excuses. Nothing wrong with the return pump contributing to the overall turnover of the display

Just love these internet guidelines, other one I like from RC is you should double the inlet and outlet pipe size fr what the pump has.

[sphelps]

Originally Posted by mark

other one I like from RC is you should double the inlet and outlet pipe size fr what the pump has.

What's wrong with that? Sounds like sound advice to me.

[Lance]

Really, the only area of the sump that needs a slower flow rate would be a refugium that requires slower flow for the particular flaura/fauna that you are growing there.

[mark]

Originally Posted by sphelps

What's wrong with that? Sounds like sound advice to me.

yep, going to be drilling out my tank tonight for that 4" bulkhead to feed my Dart

[mark]

Originally Posted by Lance

Really, the only area of the sump that needs a slower flow rate would be a refugium that requires slower flow for the particular flaura/fauna that you are growing there.

guess depends what you're growing, got a 20g macro fuge with about 200gph from the display, found after adding a 300gph PH, get better grow with the Chaeto

[sphelps]

Originally Posted by mark

yep, going to be drilling out my tank tonight for that 4" bulkhead to feed my Dart

K so maybe not for all pumps
But for most they don't have over sized inputs and outputs so it's still good advice. Mag pumps for example have 1/2" inputs and outputs so 1" pipes would be ideal. I think darts are actually over sized to avoid this confusion.

[Lance]

Originally Posted by mark

guess depends what you're growing, got a 20g macro fuge with about 200gph from the display, found after adding a 300gph PH, get better grow with the Chaeto

Yup, depends on what you're growing. I get better Chaeto growth with higher flow too.