I switched from bleach to cal hypo as my chlorinating source since my CH was somewhat low and Leslie had 100 lb. drums that came out to a lower price than bleach. Since then I have noticed PH levels tend to rise. I am using a basic phenol red test and my cell has 7.6, 7.8, and 8.0 for readings. I had the PH down to 7.2 the other day and with in a week it was up to 7.8 to 8.0. Is the 73% granular Cal hypo the reason? This might just throw off the calcs where it was cheaper if so. I am using Leslie power pro "shock" and I just use the powder to chlorinate using smaller amounts daily and 3X normal to shock or what ever the pool calculator says when I check it (most of the time). I can't seem to find Cal hypo pucks other than from Walmart and those seem to disintegrate too quickly and are less than 73%.

Chlorine is being maintained from 3 to 5 ppm.
TA was over 120, I messed up and tried to use test strips at one point, it is now 80.
CYA 40
CH 320 last time I checked. It was below 200 when I started using Cal hypo.
side note for a plaster pool can CH get too big?
12 - 15 K gallon pool.
Pump runs 8 hr. a day.
Also the spa overflows into the pool. Since I usually let the rain fill the pool unless I hear a sucking sound in the skimmer, there is often a 2 to 3 inch drop off from the cut out for the spa to overflow to the pool water line. Could this be aerating the pool?

Also have had a somewhat hidden algae problem. Just cleaned the filter and saw where the algae that some times shows up on the walls was coming from. The DE was green as can be. Put bleach in the filter tank and let it sit while cleaning the filter.
Haven't tested while chlorine was above 6 or so.

I think I have the algae problem solved but I don't know what is happening my filter. Also just discovered the suction is low enough where I can't vacuum from either skimmer. Working on that part but not sure if it is a contributing factor to anything other than the previous algae problem.

The only other chemical I use is hydrochloric acid. I did bring up the CYA level from 30 to 40 recently so some conditioner from Leslie was used.