lets talk skimmer water depth height

Discussion in 'Protein Skimmers' started by Dingo, Jun 21, 2011.

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  1. m2434

    m2434 Giant Squid

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    Well, powerman seems to have left the building, so I'll give it a go.

    The skimmer tube is a fixed height (T), but the pump does not need to support the water within the tube, from the waterline of the sump down (D). This water is supported by atmospheric pressure. The pump only needs to support the water height above the water line of the sump (T-D=H). Therefore, if the skimmer is sitting deeper in the sump, it does not need to support as much water and can move more water as H is smaller. If it moves more water, it is doing more work in a given time and therefore using more power, as power is the rate which work is performed.
     
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  3. salt4me

    salt4me Skunk Shrimp

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    Thats what i came up with a drier skim in deeper water is best.
     
  4. Powerman

    Powerman Giant Squid

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    You don't need to explain it to me. If been generating and using power and pumps my whole adult life. I watch, monitor, and manipulate power use, amp draws, and flow rates all day long. Power use increases the more work is done... less water flow, less air flow, less steam flow.... equals less power used. Just because you don't believe it, does not make it untrue. Simple physics.

    90s don't create head pressure, they create friction... resistance to flow. All piping does, and all changes of direction does... 90s, 2 45s, same thing. Curved piping creates less friction... but it still has it. Most folks just express in terms of head loss so it is easier to understand. Head pressure is the weight of a column of fluid measured in distance. Friction losses in piping systems can be expressed as the same as if there was head pressure, but head pressure and fluid friction are not the same thing.

    Go get a pump, measure amps, put a valve on it and close it. Tell me what happens to amps.
     
  5. Powerman

    Powerman Giant Squid

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    The sump level is the sump level... however, the skimmer needs it's internal level at a certain place as per the manufacturer. Where it is best to run. So you adjust the outlet valve to set that water level where in needs to be... so that should not change.... but raising or lowering the skimmer now raises or lowers THAT level in relation to the sump water level.

    So when you raise the skimmer out of the water.... now you have all this water inside the skimmer above the sump water level.... even if the water levels are sort of close.. you also have that column of foam/water mixture that is also exerting a force on the water surface inside the skimmer. So it is that difference that is causing the differences in head pressure that effect the pump performance so much.

    As a side note.... the pump would not be so effected if it was just pumping water... but since air is also in there and it is compressible unlike water, it has a much more dramatic effect on pump performance.
     
  6. salt4me

    salt4me Skunk Shrimp

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    Take a pump and close that valve on it slowly the amps will increase. The 90 causes more friction the end result is increased head pressure. Your quote,"Power use increases the more work is done... less water flow, less air flow, less steam flow.... equals less power used." So a pump in deeper water drawing more power is doing more work than a pump in shallow water useing less power? On a pump you increase resistance you will increase amp draw, move the same 10 gallons of water just harder on the pump. On a blower moving air you increase resistance it will decrease amps and increase the air moved.
     
  7. salt4me

    salt4me Skunk Shrimp

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    That you are correct sir the deeper the water more head pressure, resulting in longer contact time and better skimming.
     
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  9. Powerman

    Powerman Giant Squid

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    Obviously you have not done that, or you would not be making the statement. I have, on a regular basis. I stand by facts.

    Deeper water shallow water is irrelevant... it all adds up to a net head pressure.... head pressure is not created by a valve, it creates a restriction... but the result is the same. Less water flow equals less power use. you can say it all night long that it is not true... but the facts won't change. I didn't make the equations, I just have to follow them.

    Your last sentence is completely opposite of what you are arguing. Sorry Bud, but you really need to do some studying... heck do some experiments... conduct some tests... let me know the out come. I have already explained why it will turn out like you didn't expect.
     
  10. Powerman

    Powerman Giant Squid

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    False.
     
  11. Powerman

    Powerman Giant Squid

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    As far as what is better, that is a whole other discussion. Nothing is "better". There are pros and cons. You can set the skimmer lower in the sump, but you will run out of adjustment in the outlet and not be able to move the water... level increases and wetter skimate is collected... reaction volume is reduced and you have no control over skimmate.

    running dryer is not "better". At some point the pump simply does not process enough, you are not turning over enough of the tank. Organics are not pushed into the cup, the reaction chamber is not fully utilized.

    Neither is "better". What is better is to run the skimmer with the proper water level in the proper sump level range. Right in the middle always worked best for me. Control of water level, decent out put, skimmate like I wanted. But manufacturers understand not all systems and sump levels are the same. They simply state what range the skimmer will operate with reasonable performance. Outside of that range is on you. They are not on the hook for a crappy skimmer in use outside of their recommendations. It's that simple.
     
  12. salt4me

    salt4me Skunk Shrimp

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    Ok a txv in a ac unit is a restriction. If that valve opens it lowers head pressure, lower amps in turn. It closes the head goes up causing the amps to go up. Take the door off an air handler the amp draw goes up on the motor and it overheats. Did my experiments for 20 years in the field. Air flow and water are total opposite of each other.