Play with the CSI calculation and adjust as necessary, that’s why I do anyway. If you play around with the CSI calculator you’ll find PH,water temp, and TA affect it the most with PH main contributor. CH is so minor that it moves the CSI very little. I’ve had my CH at 500 before and still kept CSI in range. No scale in pool, ZERO scale in SWG. Basically I’m not fretting too much over CH.