Spa jets decrease pressure after spa is filled.

[AlanDanger]

I have an older (20+ years) in ground spa with 4 jets. When the spa is empty of water, the jets are so powerful, they almost remove the plaster. As soon as the water level goes over the jets, the pressure drops significantly. The jets are clear of debris and in good condition. The pump and DE filter are brand new.

Any idea of whats causing this?

Thanks
ADanger

 

[mas985]

First, welcome to the forum!

Second, what you are experiencing is completely normal. All spa jets will feel/look stronger without the water in the spa. This is because air is far less dense than water so it takes a lot more energy to move water out of the way, than it does air.

The real question is has the strength of the spa jet with the spa filled changed recently? Why after 20years are you concerned about this or is this a recent purchase?

 

[AlanDanger]

A recent purchase...
I had a repair man come over to look at the problem. Aside from having some debris behind the jets (Plastic and junk from old homeowner neglect), he couldn't find out why the pressure drastically dropped after the spa was filled. He tried to find the air intake for the jets but was unsuccessful and kinda gave up.
We have 4 pipes connected by ball valves coming from the ground that 3 separate pool companies couldn't figure out. They all attributed it to some fountain that probably existed in the yard years ago. When I was cleaning the yard after a backwash, I saw bubbles coming from the ball valves. I investigated further and found out that the valves were kinda shoved in there probably to make to piping look presentable. It was the wrong size valve and wasn't even glued into place. When I removed the valves, the pipes immediately began to suck in air and the jets produced enough pressure to rip your skin off when the pump was on high.
Ive attached a photo of the pipes. Now that I know that these are the intakes for the jets, Can I leave it how it is or am I missing something that attaches to it? (I.E. protection from debris or varmints?)

Thanks
ADanger