I've got a raised spa attached to my pool that waterfalls down into the pool. Today I noticed that after sitting all day without the pump running, the water level in the spa had dropped much lower than normal - it looked like it dropped to about the water level in the pool (which is lower than the spa's regular resting water level, obviously).
A little searching on the forum shows that this is usually a bad check valve. However, the other threads seem to indicate that the check valve is usually located on the spa return line somewhere...I can't seem to find on my spa return line. The only thing that looks like what I think is a check valve is on the pump inlet. Any chance anyone can help me it with figuring out where/which check valve I need to try and replace? Is it possibly that one on the main pump inlet?
Below are pictures of the entire equipment pad and a closeup of what I think is a check valve on the main pump inlet. On the equipment pad, the four large vertical pipes on the left are all suction (spa to left of the Jandy valve, and then skimmer 1, skimmer 2, and main drain to the right of the Jandy valve). The large vertical pipes grouped to the right of the picture all return to the pool - in order they are spa return, backwash line to sewer (has the little faucet valve on it also), blower line, two pool return lines (depending on if I bypass the chlorinator) and finally the spa return line.
Thanks for any help!