adjusting low pH

my TA was 220, so i added muriatic acid and brought it down to 120
which also brought down the pH to a little less than the 6.8 shown on my test kit. i believe i need to add borax to raise the pH back up it was originally 7.8
I have an AG 21' x 48" vinyl liner. with a sand filter.
any idea about how much borax needs to be added to adjust pH up to the proper level
i checked the chlorine level and the 10 second reading which i think is the FC is 3 and the 2 minute reading which is the CC is 5 does that sound like what it should be for just opening pool.
i have not added the cya yet. i did put in a dichlor tab last night that will have some cya, i will go to store today and get cya. how much of that do you think i should add to get up to a safe level.:confused:

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Originally Posted by fullhouse

my TA was 220, so i added muriatic acid and brought it down to 120
which also brought down the pH to a little less than the 6.8 shown on my test kit.

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You shouldn't mess around with pH at the end of your measuring ability. It may be more than "a little less than the 6.8...". Aerating your water will raise your pH without raising the TA. If you add borax, the TA will go back up, not because of the borax, but because the pH and TA are pretty well tied together unless you aerate the pool while the pH is on the low end. Run a fountain or point your returns to the surface and leave the pump running.

You may still want to add some borax and get the pH into the reasonable range to avoid pool damage.

Like JohnT said, you need to aerate your water to bring your pH back up. Here's the link to the proper way to lower your TA without completely bottoming out your pH with all that acid, for the next time you need it.
http://www.poolforum.com/pf2/showthread.php?t=191

A FC of 3 and a CC of 5 sound a little suspicious to me, it would be a little more believeable if the numbers were reversed. However, the fix is stil the same...you need to get some bleach in there, raise your Cl level to 12-15, and keep it there until your CC reading is zero.

Your CYA container will have doseage information on the label--20-40 ppm CYA is a good number to shoot for, but I would only add half the dose at first, either through the skimmer (don't backwash or retest for at least a week, since it takes 4-6 days to dissolve) or in a tied sock in front of your return stream.

Janet

Janet,
i will follow johnt's advice about setting the return to aerate the pool. right now i cannot move the little outlet, but someone should be by soon that can.
thanks for the link on how to lower alk. will be good for future reference.
also i will add more bleach and get levels up higher, just was not sure before how high to go.
if i put the cya in a sock should it stay in the pool even when the filter is off. i read somewhere about not leaving the trichlor tabs in with filter off and wasn't sure if cya was same way.
Brenda

CYA in the skimmer is fine, it won't damage anything.

Michael