Pool and spa gunite water balancing

[dropanotherthou]

I just installed the ultra temp. The house I moved into didn’t have a heater for the spa. Previous owners ripped out the old gas heater. Anyway when I use my ultra temp heat pump I start to get scaling in the water. What is the best chemical balancing for a pool+spa?
Here’s my chem when I got scaling. I’ve currently dropped the ph down around 7 to break up all the snow flakes.
Fc 5
PH 7.6
Ta 80
Ch 370
Cya 40
Salt 3700
Pool temp 88

I’m guessing now with the spa I need to keep the ph a lower.

I’m thinking like
Fc 5
PH 7.4
TA 90
Ch 370
Cya 60
Salt 3700
Pool 90 degrees

This gives me a csi of -.21, will that be low enough when I turn on the spa heat on it won’t create scaling?

What is everyone else running with a setup like mine to avoid scaling when you heat up your spa over 100?

 

[HermanTX]

It would be helpful to increase your CYA. With a SWCG it is recommended to have a CYA of 70-80. This will also lower the CSI.
Generally in summer with warmer water, it is best to have a lower pH as well so targeting 7.4 is fine.

EDIT - might add to the above - lower TA to 60 which will help your pH from drifting upwards.

 

[dropanotherthou]

It would be helpful to increase your CYA. With a SWCG it is recommended to have a CYA of 70-80. This will also lower the CSI.
Generally in summer with warmer water, it is best to have a lower pH as well so targeting 7.4 is fine.

Yeah I was looking to increase that. For the most of the day my pool is shaded.