Would re-plumbing my suction lines make a difference here?

Jump to latest Follow Reply
M

Muskogeee

Member
Apr 28, 2025
12
Daytona, FL
Hello everyone.

I won't pretend to know anything about fluid dynamics or whatever, so I figured I'd ask here.

My pump is currently plumbed like this:
plumbing.png
In order to get enough suction to my Hayward The PoolCleaner to get to ~11rpm, I need to turn the 3 way valve to like 4:30-5:00, blocking off most of the flow to the skimmer and main drain. What happens when I do this though, is it appears that the negative pressure actually seems to cause the water to start degassing. It gets loud and I see a lot of bubbles forming in the pump basket cover.

I'm wondering if 1.5" pipe is just too small for the way it's plumbed here, and if perhaps setting it up like this would may any difference at all:
plumbing2.png

Like I said, I know nothing about this kind of stuff, but I feel like logically this just makes sense to me. :ROFLMAO:

Thank You!
 
Muskogeee said:
In order to get enough suction to my Hayward The PoolCleaner to get to ~11rpm, I need to turn the 3 way valve to like 4:30-5:00, blocking off most of the flow to the skimmer and main drain. What happens when I do this though, is it appears that the negative pressure actually seems to cause the water to start degassing. It gets loud and I see a lot of bubbles forming in the pump basket cover.
Click to expand...
More likely is an air leak and/or pump cavitation.

Does it sound like gravel passing through the pump? If so, that is cavitation and occurs when there is too much head loss in the plumbing before the pump.

If what you are experiencing is an air leak, that can be fixed by finding out where the leak occurs. Most likely it is the pump lid gasket and/or basket drain plug gasket. Inspect those for crack and use some pool lube to seal.


Muskogeee said:
I'm wondering if 1.5" pipe is just too small for the way it's plumbed here, and if perhaps setting it up like this would may any difference at all:
Click to expand...
Changing that little amount of pipe really isn't going to do much at all.

The real issue is that suction side cleaners require high suction to work properly and you need to set the valves appropriately so the cleaner has enough wheel RPM while not putting the pump into cavitation. Plus sealing any air leaks.

Post a picture of your valve setup when running the cleaner.
 
mas985 said:
More likely is an air leak and/or pump cavitation.

Does it sound like gravel passing through the pump? If so, that is cavitation and occurs when there is too much head loss in the plumbing before the pump.

If what you are experiencing is an air leak, that can be fixed by finding out where the leak occurs. Most likely it is the pump lid gasket and/or basket drain plug gasket. Inspect those for crack and use some pool lube to seal.



Changing that little amount of pipe really isn't going to do much at all.

The real issue is that suction side cleaners require high suction to work properly and you need to set the valves appropriately so the cleaner has enough wheel RPM while not putting the pump into cavitation. Plus sealing any air leaks.

Post a picture of your valve setup when running the cleaner.
Click to expand...

Yeah, cavitation is what I meant by the water "degassing". I knew there was a word for it, just couldn't think of it.

Here's a video.
 
When you see air in the pump basket as the video shows, that is an air leak. Cavitation is something you can hear but not usually see because in occurs inside the impeller out of sight. In this case, both may be happening but either way it is due to the restriction caused by closing off the valve. The big question is why you need to close off that valve so much to get the cleaner to work.

What is the history of this issue:

Is this something new that just started to happen or since day 1?

Do you use a leaf trap in the cleaner line so it does not clog?

Have you tried backflushing the cleaner line to clear any clog it might have?

What make/model cleaner do you have?
 
Last edited:
mas985 said:
When you see air in the pump basket as the video shows, that is an air leak. Cavitation is something you can hear but not usually see because in occurs inside the impeller out of sight. In this case, both may be happening but either way it is due to the restriction caused by closing off the valve. The big question is why you need to close off that valve so much to get the cleaner to work.

What is the history of this issue:

Is this something new that just started to happen or since day 1?

Do you use a leaf trap in the cleaner line so it does not clog?

Have you tried backflushing the cleaner line to clear any clog it might have?

What type of make/model cleaner do you have?
Click to expand...

I can't imagine where an air leak would be. I'll double check the gaskets on the pump cap and valves, but why would it only be when I restrict flow to a certain point?

I've always had to route most of the suction to the cleaner, and I can't have both the main drain and skimmer open, or neither the cleaner nor skimmer get enough suction. I just keep my main drain closed almost all of the time.

I don't use a leaf trap in the line. The pool is screened in so I don't really ever get any large debris.

Haven't tried backflushing the line. I'm not sure how I'd go about that.

I have a Hayward "The PoolCleaner", 2 wheel version, and I can only get it to about 9.5 RPM by adjusting the valve to just before the point that it would start making noise/bubbles. Previously I had a Zodiac MX6, and that I could only get to maybe 23 seconds for 10 rotations of the marker, which is at the higher end of what it should be. Neither cleaner is/was good at climbing the walls.
 
Muskogeee said:
I can't imagine where an air leak would be. I'll double check the gaskets on the pump cap and valves, but why would it only be when I restrict flow to a certain point?
Click to expand...
Because as I pointed out earlier, when you restrict the suction side of the pump, the pressured drops (i.e. goes more negative) so it increases the relative pressure between the atmosphere (outside of pump) and the pump basket interior so the seals have to work harder to keep air out. Any seal on the pump suction side; pump basket, drain plug gaskets, valve o-rings, unions, etc. can easily leak air in when the pressure differential gets too high or they are damaged.

Muskogeee said:
I don't use a leaf trap in the line. The pool is screened in so I don't really ever get any large debris.

Haven't tried backflushing the line. I'm not sure how I'd go about that.
Click to expand...
Set the valves so that only the path to the cleaner pipe is open and all others are closed. Then open the pump basket lid and put a hose into the inlet pipe leading to the cleaner line. Wrap a rag around the hose to seal it and turn on the water. Make sure the other side is open (i.e. no cleaner attached).

Muskogeee said:
I have a Hayward "The PoolCleaner", 2 wheel version, and I can only get it to about 9.5 RPM by adjusting the valve to just before the point that it would start making noise/bubbles.
Click to expand...
I had that exact cleaner several years ago and never had an issue balancing the flow so I suspect there may be a blockage in the line or perhaps there is a problem with the cleaner itself.

How long have you had this cleaner? Parts can and do wear out. Also, that cleaner has flow vanes that debris can get stuck in which reduces the RPM in the wheels.


BTW, no suction side cleaner can actually clean walls so it is pointless. Only robots that have rotating brushes can actually clean the walls.
 
Last edited:
mas985 said:
Because as I pointed out earlier, when you restrict the suction side of the pump, the pressured drops (i.e. goes more negative) so it increases the relative pressure between the atmosphere (outside of pump) and the pump basket interior so the seals have to work harder to keep air out. Any seal on the pump suction side; pump basket, drain plug gaskets, valve o-rings, unions, etc. can easily leak air in when the pressure differential gets too high or they are damaged.


Set the valves so that only the path to the cleaner pipe is open and all others are closed. Then open the pump basket lid and put a hose into the inlet pipe leading to the cleaner line. Wrap a rag around the hose to seal it and turn on the water. Make sure the other side is open (i.e. no cleaner attached).


I had that exact cleaner several years ago and never had an issue balancing the flow so I suspect there may be a blockage in the line or perhaps there is a problem with the cleaner itself.

How long have you had this cleaner? Parts can and do wear out. Also, that cleaner has flow vanes that debris can get stuck in which reduces the RPM in the wheels.


BTW, no suction side cleaner can actually clean walls so it is pointless. Only robots that have rotating brushes can actually clean the walls.
Click to expand...

I'll try searching for an air leak and flushing out the line after work today.

The PoolCleaner is brand new, started using it Saturday after I installed my SWCG.

Thanks for the suggestions!
 
You must log in or register to reply here.
Top Bottom
Back
Jump to latest Follow Reply