Hi, just wanted to give a heads up to prevent trouble for others! I *think* that I've fixed the problem, fingers crossed. Last week, when I went out to use the spa in the morning, the water level was low and the pump was shut off. I inspected the pump (4 HP, Waterway Executive 56) and saw water pouring out around the impeller shaft. We brought it in and the shaft snapped as it was corroded.
I replaced the pump and reinstalled it.
2 days later, the spa was turned off again, this time with the message of DRY flashing.
I checked the connections, noticed that the prefilter was empty. Added water, turned it on, same thing happened.
The pump seemed to be priming itself but then I could hear that a lot of air was getting into the pre filter. I finally lifted the cover right off the tub and was surprised to see a lot of large leaves, completely surrounding the drain. I vacuumed them out, filled the filters again, and I think that the problem has been solved- the leaves were clogging the drain and drastically reducing water flow!