Richard, yes, it is elevated 18 inches. my calcium hardness level is around 300, my total alkalinity is around 105 (both these nos from pool shop analysis from 18 mos ago). the temp varies greatly with the time of year; right now it is 53 degrees. in the summer, it will be 85-90 deg. i just checked temp in both, and they are both 53. the pool and spa share the same filtration equip, and when the pump is running in its daily routine, the spa is overflowing, mixing spa water with the pool water. The spa has jets, but i just checked the ph in the pool and spa, and they are the same (7.8) as for the FC, i just checked it in both and have none showing up in either spa or pool. This time of year, with the water typically in the 50's, i turn off the generator cell and use a floater with a tablet. water usually stays clear, and i adjust accordingly. i know the generator cell has a definite life span, so i try to conserve its use when i can.