Draining an in-ground fiberglass spa

[sambeard5]

I just moved into a house with a separate in ground fiberglass spa and pool. All the maintenance I read about spas is to drain and clean every few months. I asked the company that put in the pool and they said not to drain the spa completely, but then how do I replace the water? I was thinking taking it down about halfway (which they said was ok but were pretty noncommittal), then adding water via hose while simultaneously draining with a sump from the bottom to get a bit more water exchange without completely draining. Does this make sense?

 

[mknauss]

Welcome to the forum

Are these separate bodies of water with separate equipment?

 

[sambeard5]

Yes totally separate bodies and separate equipment.

 

[mknauss]

Ok.
What are the test results that show you need to drain the spa?