higher ph ?

[airraid1999]

would the addition of freash city water raise ph ? i added about a inch in a 21' 52" deep pool ph went from a cosistant 7.4-7.5 to 7.8-8.0 before i go to lower with muratic acid should i wait a day or so ? also my fc dropped from a cosistaint 13.0 to 7.6 ? why using 1 gal 6% bleach weekly along with 1 3" tab about every 10 days this has maintaned good # through 11 test from 6/7/11 to present # are
7/15/11 7/29/11
temp-88 temp-90
fc-13.0 fc-7.6
cc-0.0 cc-0
ph-7.5 ph-7.8,8.0
ta-150 ta-150
cya-60 cya-55
ch-200 ch-200
si-0.0-0.1 si-0.3

[BigDave]

Are these numbers from your own test kit? - test the city water see if it's really high. Have you had alot of splashing swimmers lately? Areation can raise pH and swimmer load (especially with sunscreen) can consume free chlorine.

[airraid1999]

from taylor test kit and yes city water is high in ph just wnder if a inch of water would do this also the free clorine is lower ? could be burn off as we have had many days of HOT SUN but i have added bleach the same way all swim season just i added water last night along with the bleach 2 oz. of polyquat algicide and 1 tab in floater only difference from most all of other test is the water addition ? but i would think city water would not affect fc that bad??????

[airraid1999]

keep in mind water is crystal clear!

[BigDave]

I'm glad your water is clear - I wish we could use our pool!
The water treatment regimen described here is more like a feedback loop than a fixed recipie. Test your water on a regular basis then (if it's off) adjust to bring it back to where you want it. This method automatically compensates for changes in bather load, sunlight, heat, city water, etc. as you base your water treatment on measurements of your water.
So... you add more bleach... not because you added city water but because your FC is lower than you want it. You add acid... not because of city water but because you pH reads high.
I would make sure the pool is well circulated so you're not seeing a sampling error - maybe take a couple more readings from different parts of the pool.
I agree that it seems strange that one inch of makeup water should throw you off but... that's what you measure.
BTW, as I understand it, some city water systems are sanitized with chloramines which could cause high chlorine consumption. Did you find CC in your makeup water? Also the polyquat may cause chlorine consumption.

[airraid1999]

i did take another ph reading and in another part of pool its still high but not as high as far as what is needed to get back i just wonder if it could be that i have my return more upward as i did 2 weeks ago i that case i was trying to get more water displacement and ripples effect instead of really no surface water movement in the lower setting i do run my pump on low all the time but since the water is and has stay crystale clear i will run more test later before i do anything its worked all this way dont know why it would change will get back with ya when i do another compleate test this evening, thx