CLS turnover and SPS

Discussion in 'Pumps and Waterflow' started by Neil H, 21 Dec 2009.

  1. Neil H

    Neil H Moderator MASA Contributor

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    Hi All,

    So I was wondering ....

    lets say you have a 1000L tank and you have a CLS with a manifold with say a 10 000L per hour pump plumbed in ........

    do you say right i have 1000L and a 10 000L pump therefore my turnover is 10X

    OR

    Do we say no no we have 10 000L coming from the pump to the DT and 10 000L going from the DT to the pump via the manifold, therefore we have 10 000 + 10 000 divided by the DT volume of 1000L therefore we have 20X water turnover ???

    I have been doing the calcs for SPS and for a moderate sized tank (700L plus) to achieve 40X turn over is not easy to achieve 60 or 100 times it is frightening

    i am specifically interested in what the SPS guru's think here
     
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  3. RiaanP

    RiaanP Moderator

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    To add the outgoing to the cls pump will depend on the suction area. Small single hole, yes sure, then I will add it. But large area, like overflow or long drilled pipe I doubt if it will be correct to add it.

    But small hole will suck your anemones etc in. So to be inmate friendly the suction of a cls is normally weak. And therefor I think it is incorrect to add it.
    At most, maybe add 10% (if you really want to get big numbers)
     
  4. Neil H

    Neil H Thread Starter Moderator MASA Contributor

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    i hear your logic riaan, but it is still 10000L per hour moving through the tank, diffused or not, if your tank is only 1000L that is the equivilent of draining your tank in 6 mins ..... even over a large manifold the reverse flow is a lot........ imagine 10 000l going over an overflow every hour...... then multiply that by 4 to get to the SPS 40 turnover requirement and thing start to get hairy ..... if you achieve 40X flow, that is tha same as draaining your tank in a little over 90 seconds !
     
  5. Mekaeel

    Mekaeel Moderator MASA Contributor

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    Bang the flow in your DT Neil!
    eg. My DT is +-576l exc. sump.
    My flow in the DT is 2* 13 000lph Tunze 6105's and 1 * Polario 22 000lph. I still feel it is not enough though.
    My flow from tank to sump is around 1200 lph (taking into consideration head loss).
     
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  6. Neil H

    Neil H Thread Starter Moderator MASA Contributor

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    Meks, I am aiming for about 50x in the DT and the localized in the SPS area close to 100x

    i am still not clear on my understanding of the flow calcs on the cls though...... to put it another way i have 2 drums with a 10 000L per hour CLS system between the two.... in drum one i remover water at a rate of 10 000L per Hour, in drum 2 i add water at 10 000Lph, what is the flow rate / current generated by the system... 10 000 or 20 000 ?

    The only way i can come close to achieving this is with an external pool pump
     
  7. RiaanP

    RiaanP Moderator

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    ok, but, is that not the same flow? The 10000 L/h suck and blow, just like a powerhead in the tank. And the powerhead is only rated by the water exiting the pump. The powerhead also do create movement around its pickup, but here it is not included into the total turnover calculation.

    So base on powerheads I do not think the inlet to a CLS should be added into the calculation to work out the total tank turnover rate.
     
  8. RiaanP

    RiaanP Moderator

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    Another way to demontrate it is with a garden water feature, one of those with connecting overflow bowls or drums or pots. For example 3 pots, top pot spill over to next, and that to the bottom pot. And bottom pot got one 10000L/h pump in it.

    The flow in this water feature is 10000l/h, Each pot got 10000l/h going through it and combined it still have 10000l/h flow from the top to the bottom.
     
  9. Neil H

    Neil H Thread Starter Moderator MASA Contributor

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    i hear what you are saying, but if we are talking about lets say a pool pump at 30 000 LPH plumbed into a 1000L tank, the intake "current or flow" is going to be HECTIC ..... in this closed system ....??
     
  10. RiaanP

    RiaanP Moderator

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    Yip, that is true, and it will suck in any fish in that half of the tank.

    Well if it does create enough suction to feel a definite pull of water, yes, then I think you could add a percentage to the overall waterflow. If the suction is gently or wide and disperse, I do not think it should be taken into account. Or the number will be so low and insignificant.
     
  11. Falcon

    Falcon

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    dont add it..its just a gross measure to give us an idea a benchmark so by adding it and cheating your not doing yourself any favours as we all have calculated that benchmark without adding the return downfall...remember you can have a sps tank with 20 x turnover that does more for detritus removal than one with 40x turnover!

    how is this possible?well its all about flow patterns more than brute force;) so plan the water flow properly with water and rocks in before you add anything to get it right(right is the point where detrutus does not settle easily and stays suspended preferably indefinitely)

    the sps themselves do not need 100000 liters per hour flowing across them lol ITS MAINLY ABOUT DETRITUS removal;)
     
  12. Neil H

    Neil H Thread Starter Moderator MASA Contributor

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    its not that i am trying to cheat falcon, far from it, what i am trying to do is design a bullet proof system and then implement it.......

    I find it interesting that you say the flow is mainly about detritus removal ....... While i agree that that is certainly a component (and not withstanding the adaptability of corals to various flow regimes not nessicairily found in their natural locations) I believe there is far more to it than simply removing detritus .... such as providing adequate oxygen.... but in my opinion they need flow for the sake of flow ..... having dived all around the world, every spot i have ever dived with stunning SPS has been in a very high flow turbulant zone.... they are adapted to this and hence their adaption is a requirement in our systems.

    I have discussed this problem with several reefers and while there is some concensus there is ALWAYS an exception....... For example have a look through what you would consider the top 10 SPS dominated tanks on this forum..... i bet you 9 of thoe 10 if not all of them have 40X or more turnover ..... why would this be done if 20X would suffice? I dont think the answer lies in detritus removal i think it lies in understanding the flow requirements and importantly the random nature of the flow.... 40X laminar flow is of no use for example....... Someone who has clearly got this random flow right is Glynn Foreman, who as it was pointed out to me last night by a fellow reefer had a turnover in the region of 11X (i stand under correction here) and a STUNNING tank ........... Maybe it i more about random flow than it is about turnover....???

    not trying to be argumentative, just trying to understand things
     
  13. leslie hempel

    leslie hempel Moderator MASA Contributor

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    Neil it would make sence as the oxegenation is being brought to all area's of the tank as well as schuffling the detritus due to the random wave action..

    but even random wave actions will become prone to deadspots unless the flow pattern is altered from time to time.. :)
     
  14. Falcon

    Falcon

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    100% my point exactly....

    you see i said MAINLY for detritus removal i did not say ONLY for detritus removal.

    My reason for saying this is because even 11-20 x turn over rates provides them with more than enough flow to release leftover foods and 20 x turnover DEFINITELY gets them enough oxygen if the water is oxygenated in other parts of your tank(skimmer,surface movement,overflow etc).

    another factor on those reefs you talk about where the corals are most colourful is the low nutrient levels and we try to emulate this by eliminating detritus settlement,hence i say it is the main reason....i have also got a few sps species to colour up and grow nicely during the last four years with a lousy 10000lt'h in a 548liter display.....at first they did not colour up only grew alot and stayed brown, but once i lowered the phosphates using lanthanum chloride they started colouring up and continued growing even though they were not in a high flow area.

    hence i have concluded that the corals do not need the high flow directly to thrive at all.rather that the high flow helps US achieve preferable conditions by keeping nutrients low.
     
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