Hot tub water level dropping (hot tub + pool connected)

[freeflynick]

Hello!
I am looking at getting rid of my pool guy and doing the work myself.
One of the first things I want to address is the water level in the hot tub drops when the pumps are off. This was not always the case - it has been happening for the past few months.
The pool guy is no help (one of the reasons I am ditching them!) so I am hoping someone on here might give me some pointers on troubleshooting the problem.
Thanks!!
Nick

 

[JasonLion]

Welcome to TFP!

Usually this is because of a bad or clogged check valve on tub spa return line. Hopefully you have the kind of check valve that can be opened and serviced.

There is also a small chance that it is instead a problem with one of the three way valves that switch between pool and spa mode, though this is much less likely.

 

[freeflynick]

Thanks for the swift reply Jason.
The first thing I need to do is identify all the components in the system and get a schematic drawn up so I can figure out what's what....is there an easy way to identify this check valve?
Also, any idea where's a good place to look for "common" pool/spa schematics drawings so I can have a baseline to work from?

 

[JasonLion]

This diagram is a good place to start. Though few pools look exactly like that, most tend to follow that basic pattern.

If you post some photos of your equipment pad we can probably help you sort things out.

 

[freeflynick]

We have the pool with two sets of fountains and the hot tub so there a few more lines than shown here, and like you said they are all different, so yes, when I get time I will take some time to figure out what I can then post my thoughts for you guys to look at and give me your thoughts.
Looks like I stumbled on a great resource here at TFP!! Thanks again Jason!

 

[Semi-retired]

Would also help if you could describe any elevation differences between pool equipment, spa and main pool - if the spa is higher than the main pool, you could be seeing a siphon effect if all the equipment valves aren't internally "tight"

 

[DAY319]

Mine does the same thing. I've narrowed it down to the Jandy Valve directly after the in-line Chlorinator since I cant locate a check valve. If I leave that open after the pumps shut off it will drain to pool level(normal hot tub water level is ~1ft above pool level). If I close it then the hot tub only drains a few inches. Anybody else have any ideas? I have an old blower that doesn't work and the pvc fitting will rotate on the Hartford Loop. Could this cause air to create a siphoning effect? I have a new one but haven't had a chance to install yet.

*first time pool owner, less than 1 month*