Flow/Turnover rate question...closed loop?

zj4play

zj4play

Member
Flow and turnover rate. I have a 29 gallon Biocube and I found a helpfull link to calculate my turnover rate. "Add together the flow rates of every pump or powerhead you have in your system, then divide that number by the size of your tank. That's your turnover". When I do this I get 333 divided by 29 equals 11.4.
That is pretty low for a reef tank yes? If I want a turnover rate of 20 then I need to get the total flow up to 600 gph.
The question is...can a add a 300 gph powerhead, then connect that powerhead to some PVC that I can run behind my rocks? The PVC would have some holes in it. The purpose would be to keep some flow in the back of the tank where the powerheads cant really reach. I should add that I want the whole setup to be in the tank...no pipes outside of it.
Opinions please

 
squidd

squidd

Active Member
My thoughts on Turnover/Suggested turnover rates...
FOWLR : (Fish Only with Live Rock) 10X to 15X Depending on species, some like Box fish/Cow fish need slower water or "some" protected areas, others like Tangs and most Aggressive do better (filtration wise) with more flow due to high waste load.
Reef, Softies only: 10X to 15X Good rate for filtration, but not too fast as some "branching" softies won't open fully if blown around too much...
Reef, Softie and LPS: 15X to 20X with "protected" areas for branching softies (see above)
Reef, LPS: 20X to 25X Excellent flow for filtration and keeping deitrus suspended and movement of micro flora and Fauna food supply as well as "waste" and slime removal from coral bedding areas...
Reef LPS and SPS: 20X to 30X More flow is beneficial to SPS, but some "protected areas" are needed for "pillowy" inflating LPS as they too do not appreciate being blown around.
Reef, SPS: 25X and up, 30X is good, more is better: Most SPS do well in high flow situations, with a combination of random and linear flow patterns (flow control, wave and surge action, mix it up) Benefit to filtration, deitrus suspension, Oxygenation, waste and aelopathy removal and micro flora and fauna feeding...
This is a "General" recommendation for "Total" turnover which is a combination of sump return and supplemental circulation devices "IN" the tank (power heads/closed loop etc...) and with any species there will be exceptions to the rule (some softies are OK in high flow, some SPS don't like getting blasted)
Much of your success and failure with these projected flow rates will come from Rock layout and flow Output direction...Due to varying Rock scape, tank size/shape, and circulation layout (rock/tank wall deflection, caves, competing/canceling effect of flow movement) You may find you need higher or lower "Pump numbers" to get the desired "flow effect" in your tank, sometimes a rearranging of rock scape or redirecting power heads is all it takes, sometimes you'll need to "UP" the pumping capacity...
You will also need to take into account the loss of flow thru pvc ran behind rocks with holes in it...Figure about 1/3 to 1/2 flow rate loss from pump rating...
 
zj4play

zj4play

Member
Ouch...that is quite a bit to digest there. Thank you for the info. Looks like I need to figure out what is best for me. I just want to keep the dead spots out of the tank.
 
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