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Thread: Unable to get the FC levels up with the liquidator

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    stev32k's Avatar
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    Unable to get the FC levels up with the liquidator

    I've had the liquidator in service for almost two weeks and I get get the FC over about 4.5 ppm. There is one skimmer and one bottom in the pool and I normally take suction from both. When both suction valves are open I can't get the FC level above 3.5. If I close back the bottom drain valve to about 1/3 open I can get the FC to about 4.0 and if I close it completely the FC will go to about 4.5. but I want to run with both vales wide open to get good circulation.

    So far I've replaced the ball valve with a needle valve and the check valve with a 1/3 psi cracking pressure check and still cannot get the FC over 4.5 even with the bottom drain valve shut. The highest flow reading I can get is about 4.5 on the rotometer and that is with needle valve wide open. I'm using 10.5% chlorine and have kept the level up.

    I wonder if I can put in a suction hose (say 1/2") from the needle valve to the bottom of the chlorine tank and suck pure 10.5% chlorine instead of pulling the diluted chlorine from the top of the tank. Has anybody tried that? I would disconnect the inlet fill hose and block off the existing 3/8" suction hose. Would that work?
    20' x 40' IG with vinyl liner volume approx. 35,000 gal.1.5 H.P. main pump, Polaris 280 cleaner W/ 3/4 H.P. booster pump
    Hayward sand filter, 3.14 sq ft, 62 gpm. Stenner 45 MPH10 chlorine feed pump. 1 micron final filter bags (home made and very effective)

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    JasonLion's Avatar
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    Re: Unable to get the FC levels up with the liquidator

    What is your CYA level? And how long do you run the pump each day?
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
    Creator of PoolMath and Pool Calculator. Other handy links: Support this site, TF Test Kits, Pool School

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    stev32k's Avatar
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    Re: Unable to get the FC levels up with the liquidator

    CYA is 40 and the pump runs for 8 hours. Test results this morning are:

    FC 4.0
    CC 0
    pH 7.4
    TA 80
    CYA 40

    Water is clear.
    20' x 40' IG with vinyl liner volume approx. 35,000 gal.1.5 H.P. main pump, Polaris 280 cleaner W/ 3/4 H.P. booster pump
    Hayward sand filter, 3.14 sq ft, 62 gpm. Stenner 45 MPH10 chlorine feed pump. 1 micron final filter bags (home made and very effective)

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    JasonLion's Avatar
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    Re: Unable to get the FC levels up with the liquidator

    Have you tried the 3/8" hose conversion?

    Drawing straight bleach would not work well at all.
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
    Creator of PoolMath and Pool Calculator. Other handy links: Support this site, TF Test Kits, Pool School

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    stev32k's Avatar
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    Re: Unable to get the FC levels up with the liquidator

    Yes, the unit came with the 3/8" conversion. What would be the problems with running straight bleach?
    20' x 40' IG with vinyl liner volume approx. 35,000 gal.1.5 H.P. main pump, Polaris 280 cleaner W/ 3/4 H.P. booster pump
    Hayward sand filter, 3.14 sq ft, 62 gpm. Stenner 45 MPH10 chlorine feed pump. 1 micron final filter bags (home made and very effective)

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    JasonLion's Avatar
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    Re: Unable to get the FC levels up with the liquidator

    Running with straight bleach completely defeats the entire purpose of the Liquidator. It would tend to feed drastically too much chlorine, and the amount of chlorine drawn will vary dramatically depending on how dirty the filter is. A much better alternative is a bleach feed pump, which would allow you to feed an adjustable amount completely consistently.

    The liquidator works on the pressure difference between the suction and pressure side of the pump. If there is too little pressure difference, it won't feed enough chlorine. However, the fact you are getting 4.5 on the rotometer suggests that low pressure difference is not your problem.

    I suggest doing an overnight FC loss test to make sure you don't have any organic problems using up more than the normal amount of chlorine.
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
    Creator of PoolMath and Pool Calculator. Other handy links: Support this site, TF Test Kits, Pool School

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    Mod Squad Bama Rambler's Avatar
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    Re: Unable to get the FC levels up with the liquidator

    Your pool is above the size that i normally recommend the LQ for but the fact that you're able to keep the FC at 3.5 says it's working pretty good. Since you just got it I'm sure you want to make it work. The thing you need to do is increase the suction head without having to close off either of the valves. The easiest way to do that is to install an orifice just ahead of the injection point of the LQ. The easiest way to do that, is to insert a 1/8" thick plate with a hole in it in a union.
    Dave J. TFP Moderator
    24' x 52" Round AGP. 2hp/¼hp SPL Power-Flo 2-speed pump. 200sqft Waterway Cartridge Filter. 45MHP2(3GPD) Stenner Peristaltic Pump
    Pool School ----- Pool Math ----- TF-Test Kit

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    Re: Unable to get the FC levels up with the liquidator

    Quote Originally Posted by Bama Rambler
    Your pool is above the size that i normally recommend the LQ for but the fact that you're able to keep the FC at 3.5 says it's working pretty good. Since you just got it I'm sure you want to make it work. The thing you need to do is increase the suction head without having to close off either of the valves. The easiest way to do that is to install an orifice just ahead of the injection point of the LQ. The easiest way to do that, is to insert a 1/8" thick plate with a hole in it in a union.

    The problem with that is where to get the orifice plate. I wonder if increasing the diameter of the hose between the reservoir and the flow control valve from 3/8" to 1/2" would have much impact? Or maybe add a 3/8" "Y" connector and install a second suction line. The main flow restriction seems to be the control valve and/or rotometer.
    20' x 40' IG with vinyl liner volume approx. 35,000 gal.1.5 H.P. main pump, Polaris 280 cleaner W/ 3/4 H.P. booster pump
    Hayward sand filter, 3.14 sq ft, 62 gpm. Stenner 45 MPH10 chlorine feed pump. 1 micron final filter bags (home made and very effective)

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    Mod Squad Bama Rambler's Avatar
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    Re: Unable to get the FC levels up with the liquidator

    Increasing the tubing size or making a parallel connection won't solve the problem. You need to increase the suction head the LQ see's. Making an orifice is easy. All you need is a thin piece of plastic and cut a hole in it. I'd start with a hole about 1/2" smaller than the suction piping. If that works, you can increase the hole size a little until the flow through the meter starts to drop.
    Dave J. TFP Moderator
    24' x 52" Round AGP. 2hp/¼hp SPL Power-Flo 2-speed pump. 200sqft Waterway Cartridge Filter. 45MHP2(3GPD) Stenner Peristaltic Pump
    Pool School ----- Pool Math ----- TF-Test Kit

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    Re: Unable to get the FC levels up with the liquidator

    Unfortunately there is not enough space in the suction piping to install a union. A 1.5" union is 3.5" end to end and there is only 2.25" available. Would decreasing the friction loss not have the same (but, maybe smaller) effect as increasing the suction pressure?
    20' x 40' IG with vinyl liner volume approx. 35,000 gal.1.5 H.P. main pump, Polaris 280 cleaner W/ 3/4 H.P. booster pump
    Hayward sand filter, 3.14 sq ft, 62 gpm. Stenner 45 MPH10 chlorine feed pump. 1 micron final filter bags (home made and very effective)

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    Mod Squad Bama Rambler's Avatar
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    Re: Unable to get the FC levels up with the liquidator

    Technically it would, but I'm afraid the increase would be miniscule. If you could enlarge all the parts it would help more, but that's expensive enough to be prohibitive.
    Dave J. TFP Moderator
    24' x 52" Round AGP. 2hp/¼hp SPL Power-Flo 2-speed pump. 200sqft Waterway Cartridge Filter. 45MHP2(3GPD) Stenner Peristaltic Pump
    Pool School ----- Pool Math ----- TF-Test Kit

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    Re: Unable to get the FC levels up with the liquidator

    Quote Originally Posted by stev32k
    I've had the liquidator in service for almost two weeks and I get get the FC over about 4.5 ppm. There is one skimmer and one bottom in the pool and I normally take suction from both. When both suction valves are open I can't get the FC level above 3.5. If I close back the bottom drain valve to about 1/3 open I can get the FC to about 4.0 and if I close it completely the FC will go to about 4.5. but I want to run with both vales wide open to get good circulation.

    So far I've replaced the ball valve with a needle valve and the check valve with a 1/3 psi cracking pressure check and still cannot get the FC over 4.5 even with the bottom drain valve shut. The highest flow reading I can get is about 4.5 on the rotometer and that is with needle valve wide open. I'm using 10.5% chlorine and have kept the level up.

    I wonder if I can put in a suction hose (say 1/2") from the needle valve to the bottom of the chlorine tank and suck pure 10.5% chlorine instead of pulling the diluted chlorine from the top of the tank. Has anybody tried that? I would disconnect the inlet fill hose and block off the existing 3/8" suction hose. Would that work?
    If you take a look at the other posts, people dont recommend the liquidator above a certain pool volume. I was thinking it might be 24K gallons. For larger pools you should use a peristaltic (eg stenner) pump
    17,800 gallon, IG pool, 595 sq feet (17x35x4.5 avg rectangle), Hayward 525 cartridge filter, diamondbrite, 2 hp 2 speed hayward tristar filter, Stenner 45mhp10 automatically chlorinating

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    Re: Unable to get the FC levels up with the liquidator

    Quote Originally Posted by march2012
    Quote Originally Posted by stev32k
    If you take a look at the other posts, people dont recommend the liquidator above a certain pool volume. I was thinking it might be 24K gallons. For larger pools you should use a peristaltic (eg stenner) pump
    Yeah, I see that now, but didn't before I got the LQ. I don't really want to spend another $300 or more on a pump until I've exhausted all the possibilities for the LQ. But, maybe someone would like a good deal on a lightly used LQ with a lot of expensive upgrades.
    20' x 40' IG with vinyl liner volume approx. 35,000 gal.1.5 H.P. main pump, Polaris 280 cleaner W/ 3/4 H.P. booster pump
    Hayward sand filter, 3.14 sq ft, 62 gpm. Stenner 45 MPH10 chlorine feed pump. 1 micron final filter bags (home made and very effective)

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    stev32k's Avatar
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    Re: Unable to get the FC levels up with the liquidator

    Just an update. I replaced all the 3/8" suction side tube and fittings with 1/2" except the flow meter and the inlet connection to the pump strainer. The flow rate will now go as high as 5.0 on the rotometer. The FC came up to 7.0 the day before yesterday and is down to 5.5 this morning after setting the flow to about 4.25. The main restriction seems to have been the inlet check valve. The local Grainger store had a 1/2" low cracking pressure check and I believe that made the biggest difference.

    I still have to run with the bottom drain valve partly closed, but I seem to be getting adequate flow because leaves are collecting around it.
    20' x 40' IG with vinyl liner volume approx. 35,000 gal.1.5 H.P. main pump, Polaris 280 cleaner W/ 3/4 H.P. booster pump
    Hayward sand filter, 3.14 sq ft, 62 gpm. Stenner 45 MPH10 chlorine feed pump. 1 micron final filter bags (home made and very effective)

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    Mod Squad Bama Rambler's Avatar
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    Re: Unable to get the FC levels up with the liquidator

    That's good to know. I'll put that in the ole noggin for future reference.

    Thanks for posting.
    Dave J. TFP Moderator
    24' x 52" Round AGP. 2hp/¼hp SPL Power-Flo 2-speed pump. 200sqft Waterway Cartridge Filter. 45MHP2(3GPD) Stenner Peristaltic Pump
    Pool School ----- Pool Math ----- TF-Test Kit

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