Unable to get the FC levels up with the liquidator

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stev32k

stev32k

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Mar 29, 2009
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Mobile, Alabama
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?
 
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.
 
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.
 
Bama Rambler said:
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.
Click to expand...


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.
 
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.
 
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?
 

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stev32k said:
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?
Click to expand...

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
 
march2012 said:
stev32k said:
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
Click to expand...
Click to expand...

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.
 
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.
 
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