Have a spa installed higher than a pool with one system....the spa overflows into a resevoir and then thru an equalizing line to the pool.....the difficulty is the equalizing line is too small 1 1/2" and the resevoir overflows...there has been a suggestion to do a water exchange at the equipment; I know you can do with 2 systems .... can you do the water exchange from pool to spa at the equipment pad using one system?..the underground equalizing line is not big enough and leafs are jamming it up and the overflow at the bottom of the spa is filling up too fast...... like you, I don't want to dig up the expensive landscape and enlarge the line or add another line any advice thanks dg