This is an update to the above thread. For anyone answering, please re-read my initial post (about me changing the filters, etc.). A couple of days after the pool guy was out and unable to unclog the blockage, I somehow managed to do it myself by sort of switching the valves for the spa and pool back and forth and somewhere in there it unblocked and I had once again had full flow through the system and full (powerful) suction at the skimmer so that I was able to vacuum the pool. So far, so good. Or so I thought. I kept having to add water to the pool, although the temps out here were still fairly cool. I didn't think much about it actually. Then the very warm weather hit in this area of the country and I thought it was just evaporation. I began to notice that when I turned the pump off, the spa water dropped. I fiddled with the valves again, thinking maybe I still didn't have the flow set right between the spa and pool. Nothing seemed to help. I then turned the pump off to watch and see what happened for a day or two. The level in the spa really started to drop and it became obvious I was losing water. It seemed to be the spa water going down and not the pool, so at this point, I'm somewhat presuming I'm losing spa water into the pool. I did some research and various sites say it is a "check valve" problem. I have no idea what a check valve is. I don't even think I have one. I have a Jandy "never lube" valve for the switching between pool and spa and an Ortega valve to regulate the flow into the spa. Could one of these valves be causing the problem? The biggest mystery is why all this happened simply because I cleaned the cartridge filters. It was precisely at that point that all the trouble started with the "clog" and so forth. Is there still potentially a partial clog somewhere that's causing the water to lower in the spa? I would find it hard to believe that I have a more serious "leak" in a pipe under the ground, because I never had a leak before simply changing and cleaning the filters. It seems too much of a coincidence that the problems started at that point. So, I feel there's still some connection between these two events.

At this point, I'm leaving the pump off for a couple of days to see how low the spa water goes down, or if it levels out and stops. But clearly, the spa water is going somewhere, most likely into the pool although it's hard to tell. I haven't done a specific level test of the pool to see if it also is losing water, although visually it doesn't look to be. I would hate to be conned into being told I had a major leak somewhere in the system when it's just a valve. The only other thing I was told was the the manifold in my filter had a slight crack in it from the weight of the filters when they get so clogged with pine needles which fall by the bushels into my pool. However, even at the time I was told this, my pool guy said it wasn't a huge deal and he said it could wait to be fixed (this was way last year). So, I don't know of this manifold crack is playing any role in water loss. If anyone has further ideas. please share! This has me at my wits end! All I did was clean my filters and put them back in and it set off this array of problems! Thanks for your help!