I replaced my Zodiac SWG with a Hayward Aqua Rite system. Now it complains about the water flow being too low when I have the pump at half speed. Odd as my Heat Pump works fine at that speed and it requires at lest 20 gpm. Is there some way of getting the Aqua Rite system to work at the lower rate? Could it be as simple as cell that needs cleaning? The cell works great when the pump is at full speed.