After almost 10 years using an undersized cartridge filter, I installed a big sand filter last June. Love the beast, EXCEPT for two things. Ever since then, pool water has been noticeably cloudy and I CANNOT get my TA & Ph under control. Since it's winter time, thought I'd worry about the cloudiness in the spring and focus on getting my chemistry stabilized. Wild fluctuations in both TA & Ph. For example, yesterday morning I measure the Ph - it's off the charts high. Blood red on the color chart. TA is VERY (~20) compared to last weekend. I like to get my Ph in range before I tackle the TA, so I add a 1/2 gallon of muratic acid. Remeasure the Ph in the afternoon and it's still a little high, TA still very low, so I add another 1/4 gallon of muratic acid and let it sit over night. Get up this morning and Ph is REALLY low (like maybe 6.7) and TA like 10. So I add about 12 pounds of baking soda. 4 hours later, TA is at 60 but Ph is sky high again - same blood red on the color chart. I've repeated this cycle about twice a month since I got the sand filter. Chlorine and CA are rock solid (~ 4.5 and 40 respectively). Any suggestions?