Leaks or something else?

[Allie!]

I have a combined in-ground swimming pool/hot tub. When I run the hot tub only, I switch the Jandy Valve over to hot tub and visa versa with the swimming pool. Leslie pool came over to change my filter (DE) and when they left, the pressure on the pool side fluctuated since I was having a difficult time priming the pump, however when I switched over to the hot tub side, it ran well and the pressure stabilized. Leslie's service manager came out and re-checked all my connections..He said that all my equipment is running well, however he is suspecting a leak..I did the "bucket test" for leaks and so far, no leaks...so what else can it be? If I hire a swimming pool/hot tub leak detection company, they will charge me an exorbitant fee just for a diagnosis...If it is a suction leak in the skimmer, the repair can cost at least $1,000 dollars...I appreciate any feedback regarding my next step?