I probably had multiple sources for leaks. The most significant was a spa light fxture - the PVC conduit most likely had an unglued joint along the way. Long story on all the attempted fixes, at the end of the day a product called Fix-A-Leak corrected the problem, where you circulate the material for 48 hours or so (with the DE filter removed) and keep it in suspension. The product finds the leak and will repair holes up to 1/8" diiameter. I also circulated the Fix-A-Leak throughout my pool system. The claim is it will fix both structural and plumbing issues. Suction side leaks are more difficult to treat with Fix-A-Leak because you have to reverse the flow and keep the PSI fairly low, so I did not do that.

My spa is 6.5 feet by 7 feet and was losing 10" of water in a 24 hour period, which is about 285 gallons per day, now it holds steady after the fix. My total water volume (pool, spa and water feature) is about 20,000 gallons. My salt loss calculations would equate to losing about 1,000 gallons per day, but I think my actual water total loss was around 600 - 700 gallons per day, with half coming from the spa light. I started another bucket test in my pool this morning.

I calibrate the salt tester with a known 3,000 ppm sample through a calibration routine built into the tester. I calibrate every couple of weeks.

In the last two weeks, I have gone from 3,800 ppm to just under 3,000 ppm, which would indicate I have lost over 4,200 gallons of water, or 300 gallons per day. When my leak(s) were at their worst, my autofill ran loudly and continuously, now its always a very low trickle.