All of that is completely normal, right?

Then, about 2 months later, I noticed that water was no longer flowing to the spa. I had to boost the RPM to 2100rpm to get water to go to spa again. Filter pressure had not changed at all, but I backwashed anyway just in case, NO CHANGE! I opened the check valve and made sure it moved freely and had no obstructions. Pool builder is stumped.
I can accept that 1500rpm might be a little slow to run the pump, but I can't understand why it has changed?

Any Ideas????

spec's:
13,800 gallon in-ground, gunite pool and spa with pebble-sheen surface and infinity edge.
Intelli-flo variable speed pump for pool and spa, whisper-flo 2hp for infinity edge. Booster pump for cleaner.
Easy- Touch 8 controller with salt water generator. DE filter.
Spa is elevated 24" above pool eleavation.
Equipment is at spa elevation.

Was that the 1st time it was backwashed?

Scott

Yes, first backwash. Pressure was only barely raised when I did the backwash. But I thought it might fix the problem. No Luck.
Last night I put the multi-port valve in "recirculate" and that allowed me to reduce the pump speed to 750rpm and see a tiny bit of circulation to the spa. But that is still 250rpm higher than originally. And originally, there was good circulation there, not just a tiny bit.

Are all the jets in the spa shooting water properly? Putting the spa in drain mode to a few inches below the jets and switching to normal mode will tell you. Sometimes some crud gets in the nozzles.

There might be some crud in the impeller too.

Scott