Spa confusion

[ptblues2]

Spa 450 gallons, 99 degrees
CC 10 (just shocked)
PH 7.8
TA 50
CH 40
CYA not sure, ran out of test regent, ordered more....I changed the water 10 days ago, so not much if any.
Borates 50 (boric acid)

I am confused about the TA. Sometimes I read that it should be 50, others 100. What do you say?
Is a calcium hardness of 40 ok for a spa?
I ordered plenty of CYA test regent, what reading will allow me to switch to bleach? Fresh fill 10 days ago, I am using sodium dichloro s-triazinetrione as a sanitizer per bathing load and sodium dichlor once a week for shock.

ptblues2

 

[linen]

CC 10 (just shocked)

Do you mean FC of 10? What is the FC and CC?

I am confused about the TA. Sometimes I read that it should be 50, others 100. What do you say?

With your 50 ppm borates, you want TA close to 50 ppm since your ph will naturally rise due to the aeration of your spa.

Is a calcium hardness of 40 ok for a spa?

What surface is your spa made of? Generally, lower is better unless you have a plaster surface. Low calcium can help prevent you heater from getting scale. Sometimes people with low CH experience excessive foaming...if that happens you can raise the CH up to 100-150 ppm.

I ordered plenty of CYA test regent, what reading will allow me to switch to bleach? Fresh fill 10 days ago, I am using sodium dichloro s-triazinetrione as a sanitizer per bathing load and sodium dichlor once a week for shock.

Do you know how much dichlor you have used? That is the best way to keep track of when to switch. Once you get to 30 ppm cya, then switch to bleach...this is ~ 3.5 oz (by weight) of dichlor for your 450 gallon tub, or about 6.5 tablespoons of dichlor.