Low pressure return jet and skimmer

[Poddle]

I opened my pool only a couple of weeks ago and have noticed that the pressure at the return jets and suction in the skimmer is much lower than normal. We had problems with our pool shed (floor rotted due to water) so had to get a new floor in. This involved moving the sand filter with the sand still in so don't know if this could have caused a problem (leak?). I've tried to eliminate each part of the system to see what could be wrong. On filter and recirculate the jets and suction are weak. On backwash and waste the suction is good. The pool is not losing water at any noticeable rate (no leaks from filter, no bubbles in pump) - I haven't had to add any water in two weeks. There is no algae problem and water chemistry is good. The setup is an 18x36 inground pool, sand filter, Hayward pump and solar heating.

I don't know what else I can test to see why the jets and suction are so weak. Any advice much appreciated.

 

[zea3]

Hi, welcome to TFP! Have you cleaned out the strainer basket on the pump? Back washed the filter well? Please post a complete set of test results. Just saying things are in range does not give us the information we need to help troubleshoot your pool.

 

[jblizzle]

Welcome to TFP!!!

Please add your pool details to your signature and as described HERE as it will help us help you in the future.

If the jets are weak on filter and recirculate, that seems to indicate a problem on the return side ... any valves that are partially closed?

 

[Poddle]

Have you cleaned out the strainer basket on the pump?

Yes and at skimmer.

Back washed the filter well?

Yes - my pool water was and has been clear since opening.

Please post a complete set of test results.

FC = 4ppm, CC = 0ppm, pH = 7.4, CH = 200ppm, TA = 90ppm, CYA = 30ppm

 

[Poddle]

... any valves that are partially closed?

There are four valves (apart from the multi-port valve) - one is for waste so must be fine. One is before and one after the pump and must also be fine as backwash shows good pressure. The last is after the heater before the return jets - I guess this could have failed but by feel it seems to work fine - how can I test it? Is it possible the multi-port valve got clogged or damaged when moving the sand filter? Should I take this apart to check (and is it a DIY job)?!

 

[zea3]

Most multi-part valves are easy to take apart and service. If you could edit your signature to include information about the pool such as pool type (above ground or in ground), surface (vinyl, plaster, or fiberglass), size in gallons, pump brand and horsepower, filter type (sand, DE, or cartridge), filter brand and size, and any water features, cleaning systems, and if there is a spa (attached or detached). It will show up at the bottom of everything you post and it is easier for us to help you if we don't have to search the thread for this information. We could give a little more info on the multi-port valve if we know what brand of sand filter you have.

 

[Poddle]

If you could edit your signature

Hope it appears this time...

We could give a little more info on the multi-port valve if we know what brand of sand filter you have.

Is it possible for the multi-port to be clogged/damaged just on filter and recirculate and work fine on waste and backwash? I'll try taking it apart this weekend - do I need to drain the filter first? Are there any tips / instructions - will I need a new gasket (no leaks right now)?

 

[zea3]

The best way I can describe how a multi-port works is like a maze with revolving walls. Each time you push the handle down and change the setting you have created a new path for the water to flow into. It is possible that a section of the path could be damaged or obstructed so it does not work as well when it is selected. You can do a visual inspection of the gasket while the multi-port is apart. The gasket should be tight against the valve with no loose, worn or torn areas. If it is loose or damaged it will need to be replaced.

You should not need to drain the filter, but if you have shut off valves between the skimmer and return they should be turned to the off/closed position.

 

[Poddle]

Thanks - I'll take it off the filter and report back. I guess the issue with having low pressure/flow is that the pool water isn't filtered as much. Is there any other risk?

 

[Poddle]

Thanks - I'll take it off the filter and report back.

As you said it was easy to remove the multi-port, however, there are no issues I can see. It is the simplest device and looks in good shape - a little cleaning with CLR and replaced the gasket and it looks like new! But no change to the jet/skimmer flow - I hope someone else can suggest something else to try??

 

[Poddle]

I am totally stumped by this issue.

Here's what I've done so far:
1. Taken apart the multi-port valve - no issues, cleaned replaced gasket anyway.
2. Taken apart all the valves and cannot find any problems - no leaks (but I replaced the seals anyway), no audible indication of sucking air.
3. Set the multi-port on recirculate to eliminate the sand filter - no change to flow, still very low.
4. Set the multi-port to backwash or waste - huge increase in suction at skimmer and good flow from waste hose. Presumably this means the lines from skimmer to pump to waste are clear without blockage or leaks.
5. Removed and cleaned the pump and checked seal at drain plugs. When working the pump basket shows no air bubbles.

I've spoken to several pool maintenance companies but none have been to check the pool yet - only one is capable of doing a pressure test. Is this what I need to do?

I presume the problem must be between pump and return jets. The only thing I can think of is that somewhere (after the pump) a pipe joint is pulling in air (I've noticed the return jets do bubble occasionally) - could this cause the pressure drop? I was under the impression that air could only be pulled in on the suction side of the pump but on the discharge side a joint problem would appear as a water leak.

Are there any pool plumbers here who can explain how the pump works in terms of pressurising the lines?

 

[jblizzle]

This points to a blockage between the multi valve and the pool. A leak in that area can not pull in air as it is on the pressure side.

 

[Poddle]

This points to a blockage between the multi valve and the pool.

Thanks - how could I test this and find out where/what the blockage is?

 

[jblizzle]

I am not sure since the multi valve is not easily removed from the path to allowa drain king or something.

 

[duraleigh]

#14 posts and have we established any psi readings, yet? I might be overlooking them, but "low" or "high" pressure really doesn't help us as much as a specific reading could.

 

[Poddle]

#14 posts and have we established any psi readings, yet?

Readings are:
1. In filter and recirculate - 26 psi (after backwash)
2. On waste, backwash, rinse - 12-14 psi

In previous years I have usually done a backwash/rinse cycle every couple of weeks or when the pressure hits 30 psi but the pressure hasn't changed much this year - maybe because the robot is new this year or because of the low flow the filter hasn't had a chance to get clogged.

 

[jblizzle]

You should not see any pressure during recirculate or waste. Might be a bad gauge, but that does not explain low flow obviously.

Does the gauge go to zero when the pump is off?

 

[Poddle]

Does the gauge go to zero when the pump is off?

Yes.

You should not see any pressure during recirculate or waste.

Perhaps this is a symptom of the problem? Is the difference in pressure between filter and backwash reasonable? Seems weird that the pressure is higher when the flow is lower but I guess there is no reason for the two to be related.