First Pool Chem Tests and a question about pH

[newfool]

Ok! I have my first sets of pool chem:
My question is at the last set of results/

At startup:

TC 1.5
pH 6.8
Alk 50

next day

TC 0.3
pH 6.8
Alk 40

Went to pool store and bought Calcium hardness additive, chlorine, Cl tabs, borax (for future), stabilizer and additional test kits (cal hardness and cya tests)

Day after adding 1g 6% bleach and other ingredients

TC > 3.0
pH 7.2-7.6
Alk 70
CH 400 (God, I am so glad I only added about 5lbs - pool store said add 19.5lbs!!!!!!)
cya 20-30

3 days later

TC >3.0
ph 7.8 acid demand test called for adding a cup of muriatic acid
Alk 70
CH 400
CYA 30

So, my question is if I add muriatic acid as called for to decrease my pH wont my total alkalinity go down? Wont I end up chasing both ends back and forth? Or am I missing something?
12k gallons, rainbow chlorinator using trichlor? pucks, 10hr run time on pump from 8AM-6PM (about 1.2 turns), pool in full sun inside screen enclosure in Florida. 85-90 degrees. Not much rain as of late.


Thanks!

 

[JohnT]

Don't trust your pH reading while your chlorine is high. High chlorine interferes with the pH measurement.

Moving pH only changes TA temporarily, but the main function of TA is pH stability, so pH is the important parameter.

 

[newfool]

Ok, cool! Should I just wait until I see the Chlorine start to drop to about 1.5 before doing anything?
Thanks again.

 

[duraleigh]

No. You should be able to test pH accurately somewhere around 5-10ppm FC. Not sure why John T thought it was too high.

More importantly, 1.5 is too low for your FC keep it @ 2-4ppm constantly.

Check out normal values up in "pool school" "ABC's of water chemistry"

 

[newfool]

Duraleigh,

My test kit only tells me TC, I am assuming right now that it is all FC - no bather load, fresh startup pool. I sent you an email asking about your test kit and the range reported on the pH test block. I figure I would just ask you here as well, does your kit have a wide range on pH? I just want to get an accurate reading on pH if possible.

Thanks in advance

 

[Guest]

Duraleigh,

My test kit only tells me TC, I am assuming right now that it is all FC - no bather load, fresh startup pool. I sent you an email asking about your test kit and the range reported on the pH test block. I figure I would just ask you here as well, does your kit have a wide range on pH? I just want to get an accurate reading on pH if possible.

Thanks in advance

Check out this link:
category/pool-school/pool_test_kit_comparison

 

[newfool]

TY Waterbear. What is meant by a large or small comparator? Is it the size of fluid held or just the physical size of the plastic. Also, the Taylor kit gives you .2 pH gradations, is it that important to be that precise?