Very High Open Loop Flow Rate not needed

[wooden_reefer]

I am of the opinion that the open loop flow rate (I mean the loop that drains into the sump) need not be very high.

There is the concept of dwell time thru filters etc.

I think a turnover rate of as low as 2, better 3, is enough.

In a 120, an open loop flow of 250 is OK, but I 'd aim at 350 GPH or so. I think much higher than 500 does not have significant benefit.

Those who think that a much higher open loop flow is desirable for a 120 reef, please explain.

[JetCat USA]

this is no new concept, the only reason for higher flow through rates is for added flow in the tank that one doesn't have via CL or power heads.

[hawk66]

I like a higher flow because the overflows skim the surface much better. There is a better oxygen exchange with higher flows into the sump. I also utilize the extra flow from the returns by spitting into 4 returns aimed at different areas of the tank. When I have slowed the tank/sump turnover I never noticed my skimmer working any better.

[RichConley]

Originally posted by hawk66
I like a higher flow because the overflows skim the surface much better. There is a better oxygen exchange with higher flows into the sump. I also utilize the extra flow from the returns by spitting into 4 returns aimed at different areas of the tank. When I have slowed the tank/sump turnover I never noticed my skimmer working any better.

Better oxygen exchange..yes/maybe.

Better surface skimming? Absolutely not. Moving more water over your overflow means that you get a thicker 'slice' of water. You pull the same amount of protiens from the surface, but theyre diluted with more water, which means more of them will just be mixed up and pumped back into the tank.

[lvreefer]

The absolute best method is to have 100% of your overflow diverted through a skimmer before hitting your sump/filters. With this method, it is more of a question of what your skimmer can handle. Weather it be low or high flow, the flow rate needs to be such that it doesn’t bypass your filtration. What’s the point of flowing 100’s of excess gallons through a sump if it’s not getting filtered. It’s my opinion to keep flow through the sump low and keep the water movement to dedicated equipment. With this kind of setup I notice better skimmer performance, less air bubbles in display area, and less heat transferred to the tank because I’m not using a huge return pump.

[hawk66]

Thicker or not, your still creating a greater vortex (not a literal vortex, but you know what I mean) That sucks the surface scum as well as detritus from a distance a slow flow does not. Sure the protein gets pumped back to the tank before it can all be skimmed out, but at least the scum is broken up and more detritus is in the sump instead of the display.

[JetCat USA]

Originally posted by hawk66
Thicker or not, your still creating a greater vortex (not a literal vortex, but you know what I mean) That sucks the surface scum as well as detritus from a distance a slow flow does not. Sure the protein gets pumped back to the tank before it can all be skimmed out, but at least the scum is broken up and more detritus is in the sump instead of the display.

Sorry but on one of the very rare occasions I'm with Rich on this, the more flow you have the less efficient your surface skimming is and the lower the concentration of proteins going to the sump/skimmer so the less effective skimming is going to be. it's better to skim it out then to keep it in constant suspension.

[hawk66]

Originally posted by lvreefer
. It’s my opinion to keep flow through the sump low and keep the water movement to dedicated equipment. With this kind of setup I notice better skimmer performance, less air bubbles in display area, and less heat transferred to the tank because I’m not using a huge return pump.

The benefit to me is the return works double duty, replacing another water movement device as well as it's associated costs.
Whether skimmer performance is influenced either way, all I can say is I never noticed a difference. Just to be clear I'm only talking 10x through the sump, so at this rate I'm not sure why you would have air bubbles.

[hawk66]

Originally posted by JetCat USA
Sorry but on one of the very rare occasions I'm with Rich on this, the more flow you have the less efficient your surface skimming is and the lower the concentration of proteins going to the sump/skimmer so the less effective skimming is going to be. it's better to skim it out then to keep it in constant suspension.

I'm just not sure how it's better to have all the detritus rotting on the display bottom or behind a rock rather than in my sump being sucked into the skimmer.

[JetCat USA]

Originally posted by hawk66
I'm just not sure how it's better to have all the detritus rotting on the display bottom or behind a rock rather than in my sump being sucked into the skimmer.

if you'll use a power head or other means to increase in tank flow you won't have it there and it'll go down the overflow at a rate in which it can be more efficiently skimmed.