Do you have to turn on the pump or does it just come out on it's own? OH and make sure there is no kink in the hose. Just read one what had a kink in the hose and it did some damage
How does the flow feel out of the returns?
If that pressure jump (12 --> 30) were real, you'd have almost no flow out of the returns. I suspect something may be wrong with the pressure gauge. Sometimes debris can get lodged into it.
Does the gauge go all the way back to zero when the pump is off?
Who told you to run it at 3000rpm?? That a ridiculously high speed to run the pump at 24/7. For startup you are simply trying to filter the water which will happen at a lot lower speeds. Running the pump that hard makes no sense. If the PB told you to do that, oh well, but it's really just a huge waste of electricity.
Yes it drops to zero when off. You may recall that our pool is plumbed for the spa spillover to be on at all times (not our preference). So perhaps that is why the recommendation was to keep the speed high. Not sure. On that point, we also used the spa bypass valve yesterday to turn off the spillover to clean our tile. Could that have anything to do with pressure changes? We put it back to spillover after cleaning.
Question about your tile installation:
What color thinset did the installer use, white or grey?
What color grout did you select?
(We selected the same series of tiles.)
Yes, I seem to recall your rather wide spillway. That would take a lot of flow to run.
When you say you have a spa bypass, what does that do? Does it shutoff the water to your spa and redirect it all to the pool returns? If you try partially opening the spa bypass so that just a little bit of the water is redirected away from the spa, what happens to the pressure?