Weird Standpipe Spewing Water on IGP w/ Spa

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I've never seen one of these before and was hoping someone could shed some light on it. The pool is about 25 years old - 13,500 gallons with a Triton II sand filter, AO Smith 2hp motor and Jandy Lite2 heater.

I always wondered what it was, until I turned on the spa jets one day and it started spewing water (see video). It has never done this in the past.

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The spa has several small jets and one large inlet w/ a grate near the bottom. I believe the large inlet is clogged because the smaller jets still produce a good stream. The last time I turned the jets on, the spa turned green and brown almost immediately. The next time I tried turning them on is when the standpipe erupted. There doesn't seem to be a noticeable change in pressure.

Large Inlet

I guess my question is, are these pipes common? and whats the best way to check for a clog. I've got one of those rubber bladders that attach to the hose. Or would a snake from Home Depot be better to start with?

 

[Richard320]

That's likely the air intake for the bubbles. Somewhere down below there's a venturi. The water's supposed to run through the pipe and air will get sucked down that pipe, and the mixed air & water exit through the large grate. But it's plugged between the venturi and the grate, so the water comes out the air intake.

Shut the valve to that, and blast or snake it out. Expect to see a bunch of mud in your spa. Once it's flowing, run the filter to spa only until it clears up. Personally, I'd try the rubber drain king first, it's less work.

 

[Optica]

I agree that the pipe is probably for air intake for the spa jets. It looks like it has been capped awaiting install of a blower or air intake control valve at some later time, but recently got damaged (maybe not recently as the broken edges do not look "fresh"). I would guess it needs to be a lot taller (above the level of the spa waterline) as all the blowers/air intakes i have seen are way high above the waterline.

So if I understood what you said, the spa return (the large opening with grate) is plugged? This sure looks like the spa return drain but i've never seen one on the side before, they are usually on the floor. The return has nothing to do with this pipe and plugged or not it wouldn't affect it. The only affect a plugged return would have is for the spa to overflow in spa mode and the pump to be starved of water. This should easily be checkable and noticed. Does the pump loose prime or loose flow when in spa mode?

If the all of the jets in the spa are flowing, then I suspect its just the air intake pipe is broken now when it was capped and sealed before. If one of the jets are plugged then maybe the back pressure is higher forcing water up and out the pipe when it didn't before? That too could be checked by making sure all the jets are working.

Let us know what you find.

 

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Ok that makes sense being an air inlet. It looks broken but appears to be a clean cut wedge taken out of the pipe. The grate in the picture is definitely where the bubbles come out; it has functioned normally in the past. There is a drain on the floor of the spa as well.

I'm thinking it was the big AZ haboob you may have heard about. I know tons of silty dust went into that opening. It must have made its way down past the venturi and clogged it up.

Thanks for the help. I'll report my findings. Unfortunately my pump is down at the moment due to an unrelated issue.