Anna,

First off, we don't know that the pH won't stay up--check out Chem_Geek's and Waterbear's work in the China Shop. We are looking at recommendations of MUCH lower T/A than before. Meanwhile, unless pH is oscillating, T/A in a vinyl pool isn't really relevant. I KNOW we always recommended T/A of 80-120, but pH is more important by far.

Second, I NEVER recommend adding the full amount of ANYTHING a calculation computes other than chlorine. 99 times out of 100 you over-shoot your goal. It's always better to add increments and test. It's far easier to raise T/A than to lower it. Better to be low and add a little more baking soda or washing soda.

Third: I use test strips everyday () primarily to tell me if my chlorine is holding or has fallen off--if I boosted my FC and it's dark purple I know FC is holding. I use the best--LaMotte 6 way or Hache Silver. The pH test on these things are WORTHLESS as is the CYA test. After years I can ALMOST get a good guess of the actual pH I currently have about 50ppm and the strips indicate I may not even have 10ppm.

So I'm not convinced the pH test is accurate. Until we know, I don't want to see durnik56 add massive amounts of anything and then have to compensate for THAT.

5000 gallons is a small pool which can be delightful, but it's also much more sensitive to dumping chemicals in by large amounts.