My thinking is CP doesn't work as well in really hard water. My water is harder than woodpecker lips!
Now that's a good one! I think I am with you on the hardness. I believe my hardness last checked was like 40 to 70 range. My PH is like 6.5 My Total AL was 20. I am going to try my best to get some lime in my pond this spring too. I got to get it in there. Thanks for your help!