When we had our pool built a couple months ago, we had a vacuum line installed. The PB suggested I not buy an automatic vacuum right away since my pool is in a screen enclosure and in his experience, they seldom need one. He was right - not much gets in the pool, plus my family is happy not to have the hose in the pool all the time. The vac line end at the pool has the safety cap on it, so it is plugged. At the equipment pad end, I've had the valve shut off.
Is there a problem with leaving the water in the 2" pipe just sit there for years? Will it get nasty and cause problems in the future? Should I open the line and let the pump flush it every few months - which I'd rather not have to remember to do? Should I drain the line and then close it off?