Suction Loss

[KNDPool]

In-Ground. My intake setup is all manual with 3 total valves. There is a primary selector that balances between what I'll call Side A and Side B. Side A is a 2.5" intake that goes to the skimmer on the far end. Side B goes to a second set of valves that lets me balance between the near side skimmer, the suction bottom cleaner, and the two bottom drains.

I just started getting suction loss. I eliminated all the obstructions and assured high water levels per usual, and then started to do some selective research. It appears now to be very simple. If I so much as crack open Side A, the pump completely loses suction and will not recover. If I leave Side A closed off, the system functions properly.

Is there a probable cause for that sort of sudden and overwhelming suction loss?

 

[Bama Rambler]

A picture would help but it sure sounds like a joint in the plumbing has come apart. Either that or something broke a pipe. Post some pics and we'll see if we can help.

 

[KNDPool]

The selector valve for the two split intakes is on the left. The picture is taken with the system running, and you can see in the screen cover that the intake is working. But if I turn the main selector from the 9 OClock position it is in now to even 8 OClock, the pump stalls out to air immediately.

 

[Bama Rambler]

And that left most pipe is skimmer "A" only?

Make sure all the fittings you can see are glued well.

If you can't find anything by looking, you can try saturating the ground under the valves and see if it helps.

 

[KNDPool]

Correct; Leftmost pipe is Skimmer A only. The two valves on the right let me balance skimmer B, pool rat, and bottom drains.

I'll soak it up. That would rule out practically everything below ground, correct?

Is it reasonable to assume that a leak of this magnitude has to occur above the water elevation of the pool? And Therefore somewhere very near the pump?

 

[Richard320]

Is there any chance the handle is not synched with the valve inside? Maybe you're shutting flow off completely instead of opening it completely?

Assuming that is all good, then I think you are correct. If the leak was below the water level, you'd be losing water. Shut off side B and stuff a garden hose sealed with a rag in the strainer inlet. Wherever water squirts out, air will suck in.

 

[Qwaxalot]

Correct; Leftmost pipe is Skimmer A only. The two valves on the right let me balance skimmer B, pool rat, and bottom drains.

I'll soak it up. That would rule out practically everything below ground, correct?

Is it reasonable to assume that a leak of this magnitude has to occur above the water elevation of the pool? And Therefore somewhere very near the pump?

Yes it is, especially if the pool is not loosing water. (If the pool were loosing water with the valve closed, the leak would have to be in a section of pipe lower than the pool surface)

 

[KNDPool]

Hunkered down this morning and dug it up. Cracked Elbow at the bottom of that intake side. I flooded the hole I dug and tried it again so that the crack was submersed under 10" of water. It still didn't work. The crack is somewhere down toward the water level, so I could have several feet of empty 2" line to pull.... I'm just glad to have the apparent problem in view.

Thanks for all your help. I'll skip right past the irony of all of this expertise lurking around a website named "Trouble Free Pool"