Flow rate - DT to Sump question

Mrs. Music · 01/15/2012, 04:24 PM

can anyone give me some direction on flow from sump to display tank for a mixed reef tank? A link to an article or thread would be great. I know this is not a cut and dry answer and their are alot of variables. I know the 20x rule is a flexible rule...just a guideline really. The tank is a custom 180 gallon, two inch drain, durso style, with 15 inch overflow. According to the drain calculator, it can handle up to 1000gph. My current pump is a Blueline HD40, and according to the head loss calculator is only getting around 350 maybe 400 gph. Even with the Vortech mp40 I am dreaming about, that does not seem like enough. So I am thinking I should get a bit larger pump. I have read that the skimmer should be well matched to the flow thru the sump. The skimmer is a ASM G3 with the Sedra 500,and has a max output of 500 gph. So if I get a larger pump, quite a bit of water is just going to be bypassing the skimmer. That just seems senseless but is it? or maybe I should just focus on getting the Vortech? blah...my brain hurts...and then I start thinking about changing the pump on my skimmer because I have a really nice Eheim 1262 just sitting around. Now my brain really hurts...

jamey1015 · 01/15/2012, 06:10 PM

Hi I wouldn't be relaying on your return pump for your tank circulation, if fact the time the water spends in the sump going threw the skimmer and refugium is pretty important and there's no sense in rushing in and out of there.

I would keep what you got going on than focus on how water is going to move around good inside your display. A pair of mp40's would be great or some bigger Tunze's or get that one mp40 and put a koralia or two in there.

thegrun · 01/15/2012, 06:16 PM

The rule of thumb is 5-8 times the DT flow through the sump, the balance of the flow coming from in-tank powerheads. 20x DT flow is okay for most soft corals or fish only, you should be closer to 40x for most hard corals.

jdm01 · 01/16/2012, 04:53 PM

I designed an external closed loop for mine. Based the design off of what I found on www.melevsreef.com. Works very well.

sandwi54 · 01/16/2012, 05:00 PM

the 20x turnover rate is not the DT-to-sump flow rate, but rather the total turnover rate inside the DT, and can be achieved by powerheads. The return pump flow rate should only be 3-5x the total water volume, after accounting for head loss. For example, on your 180g + sump (let's say 150g total water volume after displacement from rocks/sand), the return rate should be around 500-700gph, after the head loss. In fact, the return pump is typically sized according to the skimmer size. Anything faster than what a skimmer can skim is a waste of power.

uncleof6 · 01/16/2012, 05:48 PM

Quote:

Originally Posted by sandwi54

the 20x turnover rate is not the DT-to-sump flow rate, but rather the total turnover rate inside the DT, and can be achieved by powerheads. The return pump flow rate should only be 3-5x the total water volume, after accounting for head loss. For example, on your 180g + sump (let's say 150g total water volume after displacement from rocks/sand), the return rate should be around 500-700gph, after the head loss. In fact, the return pump is typically sized according to the skimmer size. Anything faster than what a skimmer can skim is a waste of power.

Actually this is untrue. The flow rate through the sump is not connected to the skimmer performance. At any given flow rate, more water passes right past the skimmer, than gets processed by the skimmer. It is the flow rate through the skimmer, that is important (dwell time.) A return pump is sized to the needs of the system as a whole, not on the size of the skimmer. The size (flow rate) of the skimmer pump is sized according to the size of the system. If this is correct, there is no reason to concern ourselves with flow rate through the sump. Higher flow rates through the sump are desirable. Nothing in the sump requires a low flow, or "dwell time."

Just as the return cannot be used to replace the vertical mixing accomplished by power heads, neither can power heads/vertical mixing, be used to make up for flow through the return pump--it is (or should be) the 'heart' of the system. They have different functions.

Mrs. Music · 01/16/2012, 08:33 PM

Thank you for all the replies.

01/15/2012, 04:24 PM	#1
Mrs. Music Registered Member Join Date: Sep 2009 Location: Sylvania, OH Posts: 636	Flow rate - DT to Sump question can anyone give me some direction on flow from sump to display tank for a mixed reef tank? A link to an article or thread would be great. I know this is not a cut and dry answer and their are alot of variables. I know the 20x rule is a flexible rule...just a guideline really. The tank is a custom 180 gallon, two inch drain, durso style, with 15 inch overflow. According to the drain calculator, it can handle up to 1000gph. My current pump is a Blueline HD40, and according to the head loss calculator is only getting around 350 maybe 400 gph. Even with the Vortech mp40 I am dreaming about, that does not seem like enough. So I am thinking I should get a bit larger pump. I have read that the skimmer should be well matched to the flow thru the sump. The skimmer is a ASM G3 with the Sedra 500,and has a max output of 500 gph. So if I get a larger pump, quite a bit of water is just going to be bypassing the skimmer. That just seems senseless but is it? or maybe I should just focus on getting the Vortech? blah...my brain hurts...and then I start thinking about changing the pump on my skimmer because I have a really nice Eheim 1262 just sitting around. Now my brain really hurts... Last edited by Mrs. Music; 01/15/2012 at 04:31 PM.

01/15/2012, 06:10 PM	#2
jamey1015 <"))))>( Join Date: Sep 2011 Location: Detroit Posts: 171	Hi I wouldn't be relaying on your return pump for your tank circulation, if fact the time the water spends in the sump going threw the skimmer and refugium is pretty important and there's no sense in rushing in and out of there. I would keep what you got going on than focus on how water is going to move around good inside your display. A pair of mp40's would be great or some bigger Tunze's or get that one mp40 and put a koralia or two in there. __________________ Reefing since 1994' 180g Clarity Plus SPS dominant Full Spectrum LED lighting 2x Ecotech MP40W-ES Reef Octopus SRO-5000 Korallin 1502 Calcium Reactor Bashsea Bio-Pellet Reactor

01/16/2012, 04:53 PM	#4
jdm01 Registered Member Join Date: Dec 2005 Location: Greenfield Posts: 904	I designed an external closed loop for mine. Based the design off of what I found on www.melevsreef.com. Works very well. __________________ John Martin Current Tank Info: 29 Gallon BioCube

01/16/2012, 05:00 PM	#5
sandwi54 Registered Member Join Date: Jun 2011 Location: Bay Area, CA Posts: 2,332	the 20x turnover rate is not the DT-to-sump flow rate, but rather the total turnover rate inside the DT, and can be achieved by powerheads. The return pump flow rate should only be 3-5x the total water volume, after accounting for head loss. For example, on your 180g + sump (let's say 150g total water volume after displacement from rocks/sand), the return rate should be around 500-700gph, after the head loss. In fact, the return pump is typically sized according to the skimmer size. Anything faster than what a skimmer can skim is a waste of power. __________________ 375g Envision FOWLR + 125g sump 40g Reef Current Tank Info: 375g FOWLR, 40g Reef

01/15/2012, 06:16 PM	#3
thegrun Registered Member Join Date: Dec 2008 Location: Garden Grove, Ca Posts: 17,023	The rule of thumb is 5-8 times the DT flow through the sump, the balance of the flow coming from in-tank powerheads. 20x DT flow is okay for most soft corals or fish only, you should be closer to 40x for most hard corals.

01/16/2012, 08:33 PM	#7
Mrs. Music Registered Member Join Date: Sep 2009 Location: Sylvania, OH Posts: 636	Thank you for all the replies.