Hot tub level drops low when the pool is off, help troubleshooting

[jlamb5990]

With the spa full and the return side shut off, take some food coloring and place it in front of each jet to see if water is flowing back through them.
If everything on the return is in good order, its time to start thinking about the suction side. Are you sure the suction valve is completely in the "spa off" position. Even a slight misalignment can allow water to drain to the pool through the pump. What is the condition of the diverter in that valve?

+1 on this here. I had your same issue @Pharbehind and it was that my suction side 3 way was over correcting (it was an actuator controlled valve and was roaring past the spa shut off position) and letting some water drain out of the spa main drain when the pumps were off. Check and make sure when in pool mode, that valve is lined up to completely shut off flow to the spa drains.

 

[Pharbehind]

Tech just left, appreciate how much time he took to walk me through my system in person. I have 3 check valves, I replaced one, checked another and determined it was in good condition, but the 3rd one I didn’t open and turns out that was the one with the problem. Attaching a photo for reference.

The two highlighted green checks were both good. You can see one is on the suction pipe, contrary to the comment above. I believe this line was solely for the water features, and it has its own pump. The highlighted red check was the one that needed to be replaced. Attaching photos of what the check looked like.

The highlighted blue flow line was redundant, the tech speculated it was original before the roof waterfall was added, so the flow to that pipe was turned off.

 

[mknauss]

The highlighted red check was the one that needed to be replaced.

That says to the Fountain. You said the Fountain was not connected to the Spa.

What is Fountain? Is that in the spa?

No, fountain is a separate water feature item.

 

[Pharbehind]

That says to the Fountain. You said the Fountain was not connected to the Spa.

Oh yeah - when the tech was here he corrected me. I thought fountain meant the waterfall, but I was wrong. He said usually spas have a fountain coming out from the middle, shooting up… mine doesn’t have that currently. Just the opening at the bottom. I guess when original they may of had that feature going, and labeled it that way?

 

[mknauss]

Good you learned about your system. We all were on the right track, but did not know that line went to the spa.

 

[Pharbehind]

For sure, I appreciate the support as I’ve learned a lot.