I like my liquidator, it makes BBB super easy.

Patapsco Mike

Member
Sep 28, 2007
12
I wonder how hard it would be to run a second suction side line, doubling the amount of liquid dispensed from the tank? Has anyone looked into how much HASA would charge for a second suction supply line with all the attachement hardware? It would be easy enough to drill another hole in the tank.

Another solution would be larger diameter lines, right? But you'd need larger everything- lines, one-way valves, connectors, etc.
 

Sabot

LifeTime Supporter
Aug 2, 2007
343
Austin, TX
Why would you want to pump more chlorine out of the Liquidator? By just taking off the check valves and opening up the meter valve, you can dump 4 gallons into your pool in 24 hrs.
 

Patapsco Mike

Member
Sep 28, 2007
12
If you check out some of the previous posts, you'll see that at least three of us are having a hard time getting good flow out of our units. Mine runs at a level of only 1 (on the meter provided) when running my pump normally. My unit is below the pool surface, so removing the check valve is not an option.
 

Miranda

Well-known member
Jan 20, 2008
161
Northeast Florida
keithw said:
Miranda,

Yes the first thing you should do is relocate the pressure line to right after the pump output. when I first hooked mine up I had a similar issue and called HASA tech support (661-259-5848) and that was their first suggestion. Increasing the amount going into the Liquidator will also increase the amount going out. I was able to solve my problem simply by removing the check valves but I can see that in your situation that might not be possible. Do you have a picture of your set up that you can post? Having the suction side too close to an elbow might affect the suction somewhat but I am not sure.
I don't have a picture, bit my setup is exactly like the diagram posted earlier. My check valves HAVE been removed. I don't get how increasing the amount going into the liquidator will increase the amount going out.....the flow out of the liquidator is independent of the flow going in...and there is plenty of flow going in. Hasa made the same suggestion (move the line) but it still makes no sense to me and I'm tired of experimental replumbing. This sounds like a great way to solve flow problems on the liquidator intake side (such as if the tank is not staying filled) but I can't see how it could possibly effect the suction side problem
 

Miranda

Well-known member
Jan 20, 2008
161
Northeast Florida
JasonLion said:
The Liquidator regulates the water level in it's tank. It won't let incoming water come in too quickly and flood the tank and it won't get outgoing water leave too quickly and drain the tank. Because of that it is limited by whichever one, incoming or outgoing, is running slowest. If you aren't getting much water in then it closes the suction side (tube to before the pump) to prevent the tank from draining. If you aren't getting much out it closes the intake (tube to after the pump) to prevent the tank from flooding. Because of all that you get the highest possible flow when there is the largest pressure difference and thus the highest possible flow on each side.
I am assuming you are referring to the float valves in the liquidator opening and closing to regulate flow. That is not my problem....the float valves are working properly. The problem is there is little to no suction at the hole in my 1.5" pipe. I f I disconnect the liquidator hardware entirely, exposing the 3/8" drilled hole in the pipe, the hole will suck air into the pump. If I hold my finger over the hole in the pipe, the pump stops sucking air, but there is very little vacuum pulling at my finger......That is the problem. It IS a suction line, but it is nearly neutral. This is not enough suction to create a decent flow rate through the tubing.

Since it is an open, non-pressurized system, I don't understand how pressure differental is relevant. As Mike explains, the system is driven by the suction side. It sucks as hard as it can, and as long as the tank is refilling, you will get a flow rate to match. The only time the pressure side would become an issue is if the flow into the liquidator can't keep up with the flow out....then the suction side float valve would close as you described, until the tank could refill. That is not my problem. I have plenty of flow into the liquidator...it is always full. the problem is it isn't being pulled out.
 

JasonLion

TFP Expert
Platinum Supporter
LifeTime Supporter
May 7, 2007
37,879
Silver Spring, MD
Miranda said:
but I can't see how it could possibly effect the suction side problem
Lets try a really simple, though somewhat extreme, example. If no water goes into the Liquidator at all then the Liquidator drains below the level of the output port and no water comes out of the Liquidator at all regardless of how good the suction is. You can't take more water out of the Liquidator than goes into it. Moving the after the pump connection closer to the pump increases the pressure, and so increases the flow into the Liquidator, which increases the total amount of water available to come out of the Liquidator on the suction side of the pump.

Sometimes it helps and in any case it doesn't hurt. This is not the only factor that is important by any means, and in some situations it won't make any difference.
 

chem geek

TFP Expert
LifeTime Supporter
Mar 28, 2007
12,083
San Rafael, CA USA
The negative pressure at the input to the pump is going to be a function of the size and length of the suction line to the pool, other restrictions of flow in that line, and the flow rate. The same is true for the line coming out of The Liquidator to the suction line at the pump though the much narrower line means the flow rate will be much lower. Perhaps your suction line to the pool is very short and efficient. Partially closing the suction valve in the pump suction line will direct more flow from The Liquidator.

Raising the water level in The Liquidator will increase the pressure at the output point, but only by that height difference and you said that it was full already (I disagree with Jason on this -- I think there is benefit to the input side if the water level isn't already at its maximum height, but I don't think there is any benefit increasing the input beyond that). Raising The Liquidator as a complete unit, making it higher than the pump suction line, will add to the pressure difference, but I don't know if it's enough to increase your flow rate by what you need. Raising it by 1 foot increases the pressure by 1 foot. You might just put The Liquidator on something tall to see what happens (assuming your piping will reach).

Richard
 

Miranda

Well-known member
Jan 20, 2008
161
Northeast Florida
Patapsco Mike said:
So really, the answer to low flow is to remove the check valve on the suction side (before the pump) rather than to drill the hole closer to the pump on the pressure side. And as I read it, no one has actually tested whether drilling a new hole closer to the pump actually works...

The flow effect is not pressure side driven. The drop in pressure happens the second I open my skimmer inlet- so it's clearly cause by the drop in pressure in front of the pump that results from increasing the amount of water available to the pump.
I think you've nailed it here Mike....since my pump is only 4' from the skimmer, perhaps my system is TOO efficient.....there is so much unrestricted water available to my pump it can push lots of water without create suction....I'd wager that those who are getting high flow rates have long runs of pipe, or other restrictions between the skimmer and pump.

But what is the solution?
 

chem geek

TFP Expert
LifeTime Supporter
Mar 28, 2007
12,083
San Rafael, CA USA
Yikes! That's it! Having only 4 feet to the skimmer means there is very little pressure drop -- mostly just from the skimmer opening itself. The piping contributes a negligible amount of pressure drop. Even at 50 GPM, a 1.5" pipe has a drop of around 13 feet per 100 feet so 4 feet would only be a pressure drop of half a foot so it's mostly the pressure drop from the skimmer opening, not from the pipe, so it's rather small.

So partially closing your suction valve that is hopefully between the skimmer and your connection of The Liquidator output to the pipe should do the trick. That just simulates having a longer pipe with greater drop in pressure. You could also try the other technique of lifting The Liquidator higher, but I think the suction valve partial closure is the far better and more easily adjustable approach.

Richard
 

Miranda

Well-known member
Jan 20, 2008
161
Northeast Florida
chem geek said:
The negative pressure at the input to the pump is going to be a function of the size and length of the suction line, other restrictions of flow in that line, and the flow rate. The same is true for the line coming out of The Liquidator to the suction line at the pump though the much narrower line means the flow rate will be much lower. Perhaps your suction line to the pool is very short and efficient. Partially closing the suction valve in the pump suction line will direct more flow from The Liquidator.

Raising the water level in The Liquidator will increase the pressure at the output point, but only by that height difference and you said that it was full already (I disagree with Jason on this -- I think there is benefit to the input side if the water level isn't already at its maximum height, but I don't think there is any benefit increasing the input beyond that). Raising The Liquidator as a complete unit, making it higher than the pump suction line, will add to the pressure difference, but I don't know if it's enough to increase your flow rate by what you need. Raising it by 1 foot increases the pressure by 1 foot. You might just put The Liquidator on something tall to see what happens (assuming your piping will reach).

Richard
(edit) Woops, I keep crossposting with you.....

I don't really like artificially restricting water flow to the pump, and I am concerned about using a ball valve continuously in a halfway open mode, but it is working and is easy to adjust this way...... Will it otherwise negatively effect the balance of my system?

I suppose another solution would be to increase the diameter of the liquidator tubing, but I don't know if I could find fittings compatible with the liquidator hardware.

I will also try raising the liquidator...even if it doesn't help the flow rate it should help with the backflow problem if I can get the liquidator water level above pool water level. (Since the backflow valves are removed, when pump is off water backflows from the skimmer overflowing the liquidator)

Do you think the attachment point is a problem (just before an elbow)? I am assuming that moving the suction line closer to the skimmer would not be any help?
 

chem geek

TFP Expert
LifeTime Supporter
Mar 28, 2007
12,083
San Rafael, CA USA
Artificially restricting water flow to the pump is absolutely, positively not a problem at all unless this pump is already very weak and having trouble outputting it's current rate of flow [EDIT] or if the pump was specifically designed for low "feet of head" pressure with high flow. [END-EDIT] It literally just simulates what would happen if that pump were connected to a longer suction line. There will be a slight reduction in output flow rate (GPM) and the flow from the skimmer at the same pump RPM. I suppose there might be some extra turbulence in the water flow headed to the pump, but people like Mark and others would know more about whether that's a problem or not.

I don't think the attachment point is that big a deal. Even a 90 degree elbow at 1.5" diameter is only equivalent to 4 feet of pipe. Of course, that would double the pressure drop compared to the 4 feet of straight length, but as I wrote before I believe there's more loss from the skimmer input than from the pipe so the elbow is probably not a big deal. Certainly partially closing the input valve on the suction line is the real answer here.

In fact, you may find that you can put back the backflow valves if you close the input valve enough. That would be an option if you find that raising The Liquidator doesn't work for you.

Richard
 

chem geek

TFP Expert
LifeTime Supporter
Mar 28, 2007
12,083
San Rafael, CA USA
The Venturi Injector needs to see a differential of pressure along the pipe in order to work (a minimum pressure differential of 20% is needed in order to work, according to the website). You'll notice that the installations tend to be around a point of restriction where there will be a pressure difference between one side and the other. The inline version creates its own lowering of pressure by narrowing the pipe diameter (i.e. the Venturi effect) which also ends up somewhat lowering the pressure at its output as well. I believe this should work since the flow rate is pretty high (so the pressure differential should be high enough).

By the way, restricting the intake flow to the pump via partial closure of the valve as you are doing now may actually make the pump more efficient and last longer since pumps are designed to operate in a certain range of pressure differential. So unless this pump was specifically designed to operate with a very low "feet of head" and high flow rate, your restricting the flow may actually have the pump last longer. This is analogous to a pump running with little or no resistance or to a pump running with too much resistance to flow. In either case, the pump vanes will have an imbalance of pressure at the pump's fixed RPM and will put a non-radial torque on the pump shaft reducing the pump's life. In short, pumps "need" and are designed for a specific range of resistance in flow (the net of resistance from suction and pressure sides) in order to operate properly. So it may very well be that your particular pump needs more resistance to flow. Do you know your pump manufacturer and model number or is there a manual that came with it that has pump curves? Also, is the length of pipe from the pump to the return(s) relatively short (i.e. also around 4 feet)?

Richard
 

Sabot

LifeTime Supporter
Aug 2, 2007
343
Austin, TX
My bad... the Venturi Injector might work best on the pressure side... I am a newbie at the pool gig, just offering up ideas for you to research.

:)