First post - Trouble maintaining Chlorine

[waterbear]

Waste is right on the money with his answer about soda ash vs. borax!
Soda ash will increase pH and TA at the same time which, usually is not desirable. Borax will have minimal impact on the TA while raising the pH. The reasons are pretty technical and really of interest only to chemical nerds like myself.

If you need to increase the TA don't buy the 'sodium hydrogen carbonate' from your (I am assuming) Bioguard dealer at the pool store. It is most likely commercial grade. USP grade (which is much purer) can be had at the grocery store for less money as Baking soda!

If your pool store is using a colorimeter for testing with liquid reagents then it is possible that your numbers won't end in a 0, BUT if they don't calibrate the instrument on a regular basis then the readings might be less accurate then those from a test strip. IF they are giving you a computer printout either the meter is hooked up to the computer or they are manually entering the numbers, either way the clerk can (and sometimes do, I have seen it) change the numbers before the printout is run. You never know. If they are using strips with a meter I would suggest to RUN and NOT WALK out of there and not believe the results. Get in the habit of doing you own testing and take control of your water. You will be glad that you did! (And yes, I DO test water for people all day at work and sell chemicals!)