crosby

Lower CYA levels work with lower FC levels, but higher total chlorine usage. The SWG works harder to maintain the level, even though you are aiming for a lower level, because more chlorine is lost to sunlight. If your CYA is at 30 or 40, testking 70-536 you can aim for an FC level of 2 to 3. The point of having ORP is that you don't need to test the FC level very often, nor do you need to adjust the SWG percentage as the seasons change. The ORP controller takes care of adjusting chlorine production to respond to increased bather load, testking 70-298 or reduce sunlight levels, or any other factors that come into play. I have never found ORP automation to be very useful in outdoor pools. It can make a huge difference in an indoor pool, testking 1z0-050 where chlorine usage varies dramatically depending on bather load. But in an outdoor pool, chlorine usage is fairly steady anyway, because most of it gets used by sunlight, which is fairly regular. PH automation is far far more useful in an outdoor pool.