Turnover Rate

[kareen]

Hi all!

I'm in the dilemma as in what should be my flowrate of return pump.... Your advises are very much appreciated.

My tank vol ~ 400l, currently running on Eheim 1060. This translate to about 3 times turnover rate after considering the height loss (1.6m) .....

1) Is 6 times turnover rate sufficient or the more the better?

2) What is the effect of having higher turnover and why?

Lastly, what is ur tank turnover rate and what pump u used and the cost.

[weileong]

Another consideration is what skimmer will you be using?

No point having 10-20x turn over when your skimmer flow thru rate is just 1x

[kareen]

I'm using Eheim 1250 for my skimmer.... I don't quite understand the relationship here. Care to explain more?

[Plenum]

It depends on wat u keeping also. From what the LS under your signature, I think 6 to ten times ok. See your parameters, if ok then ok. If keeping more demanding corals, i've seen ppl go up to 35 times.

[weileong]

sump turnover and close-loop, in-tank turn over are for difference purpose.

[kareen]

sump turnover and close-loop, in-tank turn over are for difference purpose.

Care to explain more?

[kareen]

maybe my questions are pretty dumb.... Anyone care to direct me for more reading up on this area?

[riot]

I am no expert but this is the same issue I am facing.

The sump turnover rate is the flow from the main display tank into the sump, where the skimmer is often fed from/ located. Now, no matter how high the sump turnover is, lets say 100X, it is not going to be maximized / utilized effectively if the skimmer is only going at 10X. Its like saying that no matter if you are using a SCV cable modem or a dial-up system, if the CPU is like a Pentium 2, the download speed is going to be the same. (Ok, the CPU analogy is not accurate but hey thats the best I can think of after a hard day's work). So, if you are using a beckett that does 1000gph, but you are running a 400GPH thru your sump, then your beckett is not fully maximized at its potential- that is to clear 1000GPH.

Close loop/ in tank flow is different. The flow rate within the tank is high without any regard for the filtration system. It is not dependent on the skimmer rate, as its purpose is not to be filtered thru the skimmer. Rather, it is to provide circulation within the tank to 1) exploit live rock filtration 2) suspend organic material to transport thru overflow to sump 3) ensure oxygenated water reaches all corals. So, your internal tank flow should be reasonably high, regardless of the sump flow.

So, if you run a beckett thru your 1060, you are accually underutilizing the monster. (but on the other hand, some argue that mulitple bypass might ensure full skimming but thats another story). So, try to peg your sump flow to your skimmer flow.

Hope this helps

[kareen]

riot. Correct me if I'm wrong....

return pump + internal powerhead inside the tank = Close loop/ in tank flow => min 6 times the turnover vol of tank

Quote an example :

400l tank vol

6 times turnover => 6*400 = 2400l/hr

Therefore,

pump to feed skimmer should be around 2400l/hr, a bigger size pump is a waste of money unless there is an increase in "in tank flow". This is also sump turnover rate.

[riot]

sorry kareen I dont get your question.

In tank flow should be the following equation:

Return pump+power heads (or any other device circulating water)

Sump flow: any pump/pumps pumping water thru to main tank

Sump flow should be approx same as skimmer flow. However, some people utilize the return as part of the in tank flow and hence they might want to max out the return as high as possible, regardless of the actual skimmer flow.

Note that all formulas do not take into consideration head loss.

Gee- this is getting complicated.

[riot]

Ah, just re-read your post and see where you are going.

I think this is better:

Therefore,

pump to feed skimmer should be around 2400l/hr, a bigger size pump is a waste of money unless there is an increase in "sump turnover".

[kareen]

Does this means that the sump turnover approximately equal to the pump that used to pump up the water from sump to main tank (exlude the height loss of the pump)?

Eg. 3500l/hr pump used to return water from sump to main tank at the height of 1.6m. After taking into consideration of height loss, say the pump still has 2400l/hr, then 2400l/hr is the sump turnover.

Sorry if I sound very long-winded.... 'cos I want to make this clear....

[riot]

Yes, you are right.

Do take into acount ALL pumps sending water back into the main tank. This includes the chiller (if you run it straight into main tank) as well the main return pump.

On a whole, after scrolling to your original question, 6X flow is ok for a sump flow. Internal tank should be high as possible, taking into consideration the types of corals and live stock you have.

[kareen]

On a whole, after scrolling to your original question, 6X flow is ok for a sump flow. Internal tank should be high as possible, taking into consideration the types of corals and live stock you have.

This is what I am looking for.... and I know what to get now.

[shoelevy]

sorry kareen I dont get your question.

In tank flow should be the following equation:

Return pump+power heads (or any other device circulating water)

Sump flow: any pump/pumps pumping water thru to main tank

Sump flow should be approx same as skimmer flow. However, some people utilize the return as part of the in tank flow and hence they might want to max out the return as high as possible, regardless of the actual skimmer flow.

Note that all formulas do not take into consideration head loss.

Gee- this is getting complicated.

hi riot

regarding this point, frmo wat i understand if skimmer pump is much faster than return pump it is under untilizing the skimmer rite?

well then how about the reverse?....when the return pump is much faster than the skimmer pump, how then does this affect the performance of the skimmer

[riot]

Hi shoelevy,

it all depends on what you want to achieve with the flow.

If the skimmer is faster than the return, you are under-utilizing the full potential of the skimmer.

If the return is faster than the skimmer, several things:

The skimmer is maximized.

The faster return acts as increased in tank flow, since it adds to the internal ciculation.

Generaly, it makes sense to have a good strong return from sump to tank, equal to or higher than your skimmer. However, there is really no need to redo an entire filtration/ circulation to get a 10X or 20X sump flow.

Match the return to the skimmer output, and you are already max'ing your skimming ability. I think that in tank flow is more important, esp to SPS and keeping detritus suspended for skimmer export.

Hope this helps

[shoelevy]

ah.

i see

thanks for that riot

[minsmarine]

For your info

My tank ( display is only 170L )

I use 2,800 L /hr to feed the skimmer and same model as return pump. So, I would say I am feeding as return.

In display tank

I have

700 L/hr casitner return.

7,000L/hr Tunze 6000.

and of course return from sump.

However I am start keeping SPS so find not enough flow in display tank. Therefore upgrading to 12,000 L/hr TS12 ( 6100 ), waiting for stock come in.

All depend on what u r going to keep.

[giantbicycle]

For your info

My tank ( display is only 170L )

I use 2,800 L /hr to feed the skimmer and same model as return pump. So, I would say I am feeding as return.

In display tank

I have

700 L/hr casitner return.

7,000L/hr Tunze 6000.

and of course return from sump.

However I am start keeping SPS so find not enough flow in display tank. Therefore upgrading to 12,000 L/hr TS12 ( 6100 ), waiting for stock come in.

All depend on what u r going to keep.

a good turnover rate...for SPS