Vacuum suction problem

[JAN]

Hi. Wonder if somebody has some advice for me.

 

The hoover/vacuum hole has good suction. When I attach the hose, the end of hose has good suction as well. Then, when hoovering the floor of the pool, after a minute or so, the suction decreases a lot. The water entering the skimmer basket has very little flow.

 

All worked fine, for several years, till about 2 weeks ago. I have an overflow pool.

 

The suction pipe goes to the pump and afterwards to the filter and then to pool outlets/nozzles. As you can seem the basket of the pump has almost no water going in and lots of air. 

 

Checked the filter, pump, connections and all’s as it should be.

 

Any reason why suddenly this is happening?

[teigen]

Did you check the spider gasket of your multi port valves also?

[Fruit Trader]

Possible an air leak has developed in the suction line used for cleaning. It might take several minutes for a pump to lose prime after the leaking vacuum line valve has been opened.

 

First check all accessible joints and valves for leaks on the suction side.

 

Why is the bottom drain line missing, is it because there was an inaccessible leak?

[JAN]

Yes, that is what I suspected, that somehow there is air going into the suction pipe. Will check that. Mind, you might be difficult job as most of it is underneath the deck. Or I might change all the pipework going from suction pipe to pump and beyond. What you think? Momentarily it's a bit of a mix of pipes and honestly, a bit of a mess. 

The bottom drain is OK, I never used it yet, but if I need it is there, and will just run out of the pipe in the pump room, near the sprinkler pump. 

[carlyai]

Undo the connector/valve from the pump to the filter and let the water pump out. See what the flow is like. This test will check that the problem is not on the pump output side. Probably isn't, but now you will know 100%.

 

 

[SantiSuk]

I recently (one month ago) had the denouement to having had a similar problem to yours - declining flow when pumping, poor suction when vacuuming and an obvious ingress of air in the system as evidenced by a frothy appearance of the flow at the pumps inspection lid. Also a noticeable thump had been detectable for a few moths when I switched the pump off.

I should have attended to it earlier - the suction got so bad that I could not get the flow working through suction from the pool side alone and had to partially open the valve to allow water to come from the pool bottom to supplement flow and eventually even that was not helping enough. In the last couple of months before denouement i also experienced a slight water jet issuing up from the pump lid when I switched off.

Then on the fateful day a month ago, when I switched the pump off, the thump from the system became a loud bang, the pump lid flew off about two feet high and I was partially drenched with water. The pump lid had cracked.

The Emaux pump supplier, Swimming Pools Thailand said they had no experience of such a set of events. I was going to call Emaux but first looked up the internet, googling "water exploding from my pump lid" (or something along those lines). I found a relevant post by a pool specialist who said that air visible in the flow through the pump would have been a sign of a leak and the first place to look (and most likely culprit) would be the pump lid itself. If not there it could be any of the valves, the filter or pump itself.

I sucked hard contemplating replacement of my entire system, but the internal contents of the pump room were only 3 years old (piping and main valves installed 12 years ago). I decided that if the pump inspection lid was the prime candidate I would replace that and see what happens. Bought replacement pump lids and seals from SPT and lubricated the seals heavily with silicone gel. Nothing else was changed but I did clean the reserve tank and the footer valve in there (it tends to need cleaning every month).

With great trepidation I tried it out, this time facing well away from the pump. Success! The pump returned to a quieter operation with clearly better flow and only a bit of air in evidence. When I did my first vacuuming it was evident that the pump was sucking much stronger - back to as new in fact. Still not back to performance as new in terms of a small amount of air mixed in when viewed at the pump lid but the good suction and flow rate and the comforting soft noise I get when switching off now has persuaded me to put off the full replacement of valves, pipes filter and pump. I will watch carefully for deterioration and take action well before it all goes downhill again!  

 

[JAN]

Great reply; and seems to work better now. Thanks.