Strange spa water action

[akropp]

I just put in my pool/spa recently, and before closing it up for the winter, the installer said it was fine to fire up the spa. Since it is getting freezing here overnight, I have the automation set up with freeze protection, to keep everything flowing. Now that there is water in the spa jet lines, I added the jet pump to the freeze protect program, but something about my plumbing seems to be very strange.

Prior to turning on the spa, the pool was set up to pull water from the skimmers and main pool drain on the input side, and output evenly to the spa and the pool return lines (so that clean water would enter the spa, and then overflow into the pool). The only thing that is changed now is that the spa jet pump comes on as well (it is a separate pump, with a separate set of lines that pull from the spa drain and return back to the spa); the first morning after I set this up I discovered that the spa was drained by a couple of feet. Now, the only way I can keep the spa from draining when the jet pump is on is for the main pool pump to only pull from the skimmers and pool drain, and return ALL of the water to the spa return lines. If the return valve is even a little bit open to the main pool lines, the spa drains down. It seems that somehow the spa jet pump is causing the return water from my main pump to only go to the pool.

Not sure how well I am explaining this, but not sure how this would happen; as far as I know, the spa pump/circuit is totally separate from the pool filter circuit.

 

[mas985]

Not sure how well I am explaining this, but not sure how this would happen; as far as I know, the spa pump/circuit is totally separate from the pool filter circuit.

So does the spa have it's own pump and it's own filter? If not, the plumbing/equipment is shared and it could be a check valve issue. Post a picture of your equipment pad.

 

[akropp]

In investigating some more, they are definitely attached somewhere. I am also having an issue with the jets not having any air, and in investigating that, I drained the water down below the jets. When either the jet pump or the filter pump are on, water sprays out of all of the jets, so both are clearly attached to the spa jets/returns. Also, when I have the return valve set to send water to both the spa and the pool and I turn on the spa jet pump, I can tell that the water volume increases in the pool returns as well as the spa. So it seems that when the jets turn on, they are drawing water out of the spa, and returning more of it to the pool than to the spa. The only way to prevent this seems to be to COMPLETELY shut the valve to the pool returns.

To directly answer your question, the spa has a separate pump for the jets, but is on the main pump/filter system. Here is a picture I had taken of the valves (it's night now, so can't get one of everything). The only check valve I see in the system (not pictured) is before the SWG. Top valve is return side (up is spa, down is pool), bottom valve is suction side (top is spa drain, left is pool drain, right is pool skimmers. Spa jet pump (the pipes at the very bottom) isn't visibly connected to any of the other pipes, but apparently it is somewhere.