To flow or to pump

Discussion in 'Protein Skimmers, Mechanical Filtration' started by Copperband, 11 Jun 2007.

  1. Copperband

    Copperband

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    Ok I really don't like the double thread start thing some of us tend to do, so this is not a repeat of another thread on another forum in another galaxy far far away.

    Why do so many reefers feed their skimmers directly from the overflow? This weekend I helped Carl change his config from overflow fed, to pump fed and the results were stunning (if you can call skimmate stunning). Due to plumbing constrains I also fill my DNW 150 with a pump and it works like a dream. IMHO i believe its easier to regulate the amount of water into your skimmer by using a pump than by adding ball valves and other plumbing goodies.

    Is there a scientific reason for overflow feeding or do we just do it cause we've been told to do so?

    Thanks guys!!

    R
     
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  3. Smithers

    Smithers

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    Good point there Robbie. I want to change mine to pump feed. The overflow trick is a pain. Ball values fittings time and effort to name but a few. The one bonus is that all the water from the overflow is skimmed. That is the only bonus that I can think of.
     
  4. Mekaeel

    Mekaeel Moderator MASA Contributor

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    i guess smith just explained it to us.i feel that if not directly fed,alot of water is just flowing through without being skimmed
     
  5. SIMS

    SIMS

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    Well I have changed from feed pump to overflow - I will agree it was a mission to get the correct amount of flow going to the skimmer without air but now that it's setup its working well, I was having a problem with debrits getting to the sump - now that all water is going through the skimmer this I hope will be less of an issue, I plan to put a box with some filter wool in so all the water from the skimmer outlet will pass this box and catch any unskimmed debrits....
     
  6. Copperband

    Copperband Thread Starter

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    Smithy-baby :lol: I don't agree that via overflow all the water is skimmed, all the water does go through the skimmer but its difficult to determine your "real" contact time thus if the water is really skimmed. Now via pump if your skimmer is rated for 2000L you can feed it 2000L per hour.

    Really want to see what the GURU's say.
     
  7. Alan

    Alan Admin MASA Contributor

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    The external skimmers were originally designed to run on feed pumps and then the guys started running from the overflows. Personally i prefer the pump method just makes it easier all round for maintenance purposes. The idea behind the overflow method was to skim all water exiting the tank, so if you looking for this method to work properly make sure your skimmer is big enough to handle the overflow water otherwise you have to run with a bypass and then you back to the same as running with a pump.
    My best results are obtained by feeding my skimmer with a pump from the first compartment of the sump and have the outlet of the skimmer returning to the second compartment with about a 5% bypass from first compartment to the second.
     
  8. leslie hempel

    leslie hempel Moderator MASA Contributor

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    trying the overflow method and then if unsatisfied will try the pump method with that mod with a little extra air injection on the feed pump....
     
  9. Carl

    Carl

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    CB

    The "rating" of a skimmer say 700l or 400l does this refer to the tank capacity or the throughput per hour??? Cannot find any real explination on any of the manufacturers sites.

    Carl
     
  10. Alan

    Alan Admin MASA Contributor

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    The rating on the skimmer refers to the system volume, and generally the slower the water passes through the skimmer the more contact time it has, generally i aim for 1-1.5 x the skimmer rating through the skimmer every hour.
     
  11. Copperband

    Copperband Thread Starter

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    Carl the manufactures rating is for complete system volume. But I read (I think its on Advanced Aquarist) that if the skimmer is rated for a 1000L system one should try and put 1000L - 1500L p/h into the skimmer. This ensures optimum contact time. This is why Adriaan suggested I don't feed the DNW 150 (750L skimmer) with a 2000L p/h pump and should rather use a 800-1200 L p/h supply to the skimmer.
     
  12. Mekaeel

    Mekaeel Moderator MASA Contributor

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    this topic is getting rather intersting!copperband,what LPH pump does the DNW 150 come with?is it a standard 200LPH?
     
  13. Hill

    Hill

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    The DNW 150 does not come with a pump unless you are talking of the recirculating pump. The recirc pump is a 2000l/h.
     
  14. Copperband

    Copperband Thread Starter

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    Mekaeel the recirc pump on the DNW 150 is a 2000l/ph. Thats the only pump that comes with the skimmer. I feed the skimmer with a seperate Rio Hiflow 2000L/ph pump. I'm about to change that to a smaller 1200L pump to try and ensure a longer contact time in the skimmer.
     
  15. Mekaeel

    Mekaeel Moderator MASA Contributor

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    cool.thanks for the info copper!
     
  16. Smithers

    Smithers

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    Robbie-baby, To bring this back again. I can see the advantage to plumbing your skimmer to the over flow BUT i have now got sick and tired of not being able to get a stable water level in the skimmer.
    I am also thinking of changing the ball valve to a needle valve to regulate the water that much more accuratly.
    So tonight I am going to ,once again, modify my setup. Pushing up the flow into the tank and I am going to use a 1750 LPH Haliea pump to run the skimmer.

    At least by trying both I can say which one I prefer. I think I am leaning towards the pump feed at this moment.
     
  17. Copperband

    Copperband Thread Starter

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    Gavin i just think for ease of use the pump makes more sense. In Anthony Calfo's book on coral propagation he says we use overflow water to feed the skimmer because we want to get rid of the call it oil slick on the top of the tank. My thinking is if you overflow into a skimmer chamber in a sump you still skimming the floaters.
     
  18. Smithers

    Smithers

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    I think you will as well. That oil slick will be mixed up a bit BUT it will still be pushed into the skimmer. The problem I have with using the overflow into the skimmer is that it restricts the flow you can have into your tank. I know you can put a bypass on it etc but that kind of defeats the object , well in my thought process it does.

    Secondly having the skimmer plumbed directly it causes a slight back log in the overflow chamber as there is not enough gravitational pull to get all that water into your skimmer.

    Thirdly if you even just stick your hand into the tank, the extra water that is displaced makes the level in the skimmer rise which is painful.

    Just my thoughts !
     
  19. Copperband

    Copperband Thread Starter

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    Gavin, when Carl was feeding his 4 pump Octo from the overflow once every so often the thing would have these huge bubbles and you could hear a water / air displacement sound (like a really mean gurgle 3L Ford with nitro's i tune you) next moment the skimmer would vomit 25L wet skimmate. Now with the pump feeding the skimmer that Ford has left the building and the skimmate looks like coffee.

    Now don't tell him this, but you must see how much better his tank looks, water is clearer and more growth. I could only ASSuME the skimmer had something to do with it. Many might disagree.
     
  20. Smithers

    Smithers

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    I have a durso on my tank so I get a smallish bubbles going in to the skimmer. But those bubbles are still entering the skimmer and could possibly screw up the finer bubbles. At least with a pump feeding the skimmer there is none of that.
    Looking at the debate to flow or feed I feel IMO that to feed is better. I will let you guys know how it goes tonight.
     
  21. Smithers

    Smithers

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    Just an update here, I modded my overflow last night so the overflow box goes directly into the sump. I have added a Haliea 1750 LPH pump to run my skimmer.

    I did not expect to see an improvement immediatly but I did ! I was able to set the water level in the skimmer far more accuratly than I was able to do before. I set the level in the skimmer to be about 1 to 1.5cm below the rim of the skimmer neck.
    Another thing I noticed was that the bubble consistency was far better. Before I was getting large bubbles entering the skimmer from my overflow. Skimmate started to form about 10 mins after I connected it up.

    If I look back at the time, effort and pain it was to connect my skimmer to my overflow I could kick myself.
    32mm piping, ball valves T pieces not to mention one or two little glueing mistakes.
    The cost with running a skimmer with a pump ,I think, works out cheaper. There is less headache and it really does make life easier just to run it via a pump.

    Having tried both methods , I have seen advantages and disadvantages to both system. IMO I am not going back. To pump it is !
     
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