Clarification of tun-over rate through sump

[builderguy]

I keep seeing the turn-over recommendation through the sump described as 3-5x the tank volume...but shouldn't it be total system volume?

Does anyone have a clear understanding of this?

[DreamMachine]

It's just a rule of thumb. Lower turn over rate allows the skimmer more contact time to the water and thus better skimming.

[builderguy]

I understand that. But I am building a new system that has a 280g display tank with 350 gallons of total system volume. Should I be doing that calc based on 280 or 350...or am I just "splitting hairs" here. 280g x 5 = 1400gph --- 350g x 5 = 1,750gph.

It makes a difference in pump selection etc...so just trying to get it right.

[DreamMachine]

For a 280, I would lean toward 350g x 5 = 1,750gph, 280g x 5 = 1400gph does not seem enough to me at all.

[usefulidiot213]

This is a matter of opinion..
I would not do 5x. I would do around 3 times. Because IMOA, I like to slow the flow threw the sump to give my skimmer and fuge more contact time with the water.

[jb61264]

sorry...i don't buy the logic of the slow flow rate through the fuge for more skimmer contact time.

skimmers use a separate pump to pull water into it...regardless of the water flowing faster or slower, its still pulling water in at the same rate into the skimmer body for skimming...once it is in the skimmer, whether or not the water is flowing faster or slower in the sump is mute, it will skim what is being pulled into the skimmer...and to be quite honest, i would rather have a higher flow rate (like I do) through my sump which seems like it would increase the chance of a majority of my systems water entering into the skimmers body over the course of time

Not trying to create any arguments here and there may be scientific evidence to prove me wrong...this is just my opinion

I have a 75 gallon display with a 55 gallon sump...I use a Mag 18 pump for my return on a beananimal failsafe overflow so I have pretty good flow going through my sump. Granted I tee off my return to a fuge chamber, but I still figure I have around 600-700 gph coming out of each return (corners of display tank).

[strike2867]

Originally Posted by jb61264

sorry...i don't buy the logic of the slow flow rate through the fuge for more skimmer contact time.

skimmers use a separate pump to pull water into it...regardless of the water flowing faster or slower, its still pulling water in at the same rate into the skimmer body for skimming...once it is in the skimmer, whether or not the water is flowing faster or slower in the sump is mute, it will skim what is being pulled into the skimmer...and to be quite honest, i would rather have a higher flow rate (like I do) through my sump which seems like it would increase the chance of a majority of my systems water entering into the skimmers body over the course of time

Not trying to create any arguments here and there may be scientific evidence to prove me wrong...this is just my opinion

I have a 75 gallon display with a 55 gallon sump...I use a Mag 18 pump for my return on a beananimal failsafe overflow so I have pretty good flow going through my sump. Granted I tee off my return to a fuge chamber, but I still figure I have around 600-700 gph coming out of each return (corners of display tank).

Unless you have a gravity fed skimmer.

[jb61264]

Originally Posted by strike2867

Unless you have a gravity fed skimmer.

Good point...I was only considering in sump skimmers that use a separate pump. I'm not familiar with gravity fed skimmers but if they are a separate 'overflow' independant of the systems overflow, then I would still say a higher flow rate through the system would be more beneficial towards ensuring more of the entire systems water makes its way to the skimmer over time...but of course, yes, you would want to increase skimmer contact time by decreasing the flow through the skimmer via gravity.

[BFG]

I am in the lower flow through the sump method. I had tried a higher flow rate turn over and algae was dominant in the display tank. Changed to a lower flow through the sump and algae was able to appear near the surface of the tank eg overflow comb and on the tunze wave maker. I am currently using a Eheim 1262 for my 120g tank. My advise is to have the return pump flow rate be as close to the skimmer pump flow rate.

Started with a Deltec APF600 with a Eheim 1250 feed pump and a Red Dragon 8 2m3 return pump. Skim mate was dark and nasty and algae was prevalent in the display tank.

Currently with a BubbleKing SM250 with a Eheim 1262 return pump. Skim mate is muddy and algae can only grew near the water surface ie overflow comb and on the surface of 2 Tunze 6100 wave maker.

Hope this helps!

[solitude127]

builderguy, what skimmer are you using or going to use? Another reason for slower flow rate through the sump is for less micro bubbles in the DT. The slower the flow, the better the chance of the micro bubble to dissipate in the sump.

[Paco]

I am currently using a Eheim 1262 for my 120g tank, too, and I think it's just about perfect. That's around 4x to 5x flow (about 600 gph w/headloss). Builderguy, have you considered a Tunze Master Recirculation Pump? It's spendy at nearly $400 but if it's like other Tunze items, it should be fabulous.

[builderguy]

i have a custom skimmer...think of it as an H&S recirculating with a bubble plate. I use a Ehiem 1262 with the EuroReef needlewheel for the ricirc pump....still looking for a feed pump to feed it 500-600pgh