Need opinions on IG pool leak

My IG pool has been leaking for a long time. For various reasons, I have just been putting more water in it. Now I am determined to fix it.

Various experiments and observations over time have lead me to the conclusion that there is a leak in the pressurized pipe used for used by the Polaris. I filled the pool and did not run the main pump or the Polaris pump for 4-5 days and the water level stayed constant. Turned the pump back on and the water level dropped. Another indicator is that the Polaris is extremely lethargic, suggesting that it may not be getting enough water to make it move at normal speed.

I had a pool repair guy out doing some work on my pump and he looked for possible openings around the skimmer and caulked a couple of places. It didn't help.

One of the mysteries is that I'm not seeing any water coming up from under the pool deck. All that water has to be going someplace!

Another discouragement is that the Polaris supply pipe in question is under the pebbled/concrete pool deck and I've not been able to identify a spot where I should start tearing things up.

Question: Give the above information, how confident would you be that it's the Polaris supply pipe?
Do I need a leak detection service?

Having battled algae all summer and this leak for a long time, I'm starting to calculate how many cubic yards of dirty I'd need to make the pool into a flower garden. ;)

So, did you run what you call the main pump and leave the Polaris pump off - and then still not see a drop in water levels?

When I run the main pump, I still lose water because the water returned to the pool also goes through the pipe that feeds the Polaris.

If either pump runs, I lose water. If neither pump is run, I do not lose water.

Bob

Welcome to the forum Bob.
I think I would feel pretty confident about the location too. If it was a leak around the skimmer or on the suction side the situation would be reversed. Losing water either all the time or only with the pump off. As for the missing water, it could have just found a channel in the ground and is going somewhere else. I had a leak at the deep end of my IG years ago and the loss rate was about 50 GPH. It leaked for a couple weeks before I found and patched it. No trace of the missing water. Also remember that as the water leaks out it won't go uphill to the surface of the ground if that is above the pool water level. Looks like you have some digging to do. Keep us posted on the progress.
Al

Thanks for the confirmation of my diagnosis, Al. I am very much enjoying my membership. Much more accurate and reliable advice than I get at the pool store!

Bob