Yeah... Membership :-)

The VSP outlet connects to the VariFlow intake with a 90° elbow through a total of perhaps 2 or 3 ft (or less) of piping, i.e. both are quite close and it is hard to know for sure where the noise came from. I'm away from the system right now but will recheck soon to see if I still hear the noise. It was clearly present when the new equipment was just installed and had to filter back to clear a pool that over 2 weeks off had become dark green, almost black. (After close to 15 years, the whole pad had aged to the point of needing replacement and delays occurred.) Once the water was clear again and the filter washed, I am not sure the noise remained as strong. As I said I will recheck. What remains however is the air at lower speeds under the pump lid. Pressure in the filter is low at low speeds and within range at max speed, good.

My plan is to screw all Jandys tight, make sure all baskets/skimmers are free of debris, perhaps prime the pump by hose and see whether air enters the pump lid when none should be expected (right?): I surely hope not.

It would be sad not having peace of mind when running at full speed and using the spa to avoid possible cavitation. Is there a way of making sure it is cavitation and not something else? If it is, I wonder whether I should call the installers back to solve the problem. Could giving more space between VSP output and valve intake help?

Re pump run times, I've found a 1984 study that yes says you can do away with turning over once a day but everybody else including the DoE today recommend the one-a-day turnover rate. At 600rpm to use only 43/60 Watts max instead of IIRC about 200 Watts at 1000rpm, there probably is some money to save. I need to sit down and do the maths. At 600rpm one calculator gave me a turnover time of 22h, long but energy efficient (and it makes the spa nicely spill over into the crystal clear pool, which BTW is scheduled for resurfacing next week). This could be cheaper than 2x3h at 3450rpm, the speed at which I guess my old SP3015X20AZ single-speed pump was revving. Isn't that the whole point of a VSP, running it longer at much lower speeds? Not sure I would save more over time had I purchased a simple one speed pump and running it no more than 4hours a day but at 3450rpm.

In any case I shall have my Taylor kits on the way very soon for BBB. Can't wait! I wonder whether I can continue using my stock of Trichlor tablets or whether I should only pour generic chlorox... Need to continue reading!