I agree with above posts that its not reliable to try to get
valid pH test results while in the throes of the slam process.
High levels of chlorine, especially levels over 15ppm, can give
give 'False-high' pH test results.
that being said,
... remaining algae free, (post Slam) is easier with lower pH levels.
Chlorine has More killing ability for bacteria and algae at 7.4, i.e. than it does
at say, 7.8.
I should know, ive lived thru the SLAM process, more than once.
(and im too embarrassed to say how many times I had to do it before putting the pieces together.
the first few times i successfully turned a black/green swamp
to sparkling blue pool, (buying and dosing and adding all pool chemicals myself, as well as Brushing and Vacuuming pool plaster, and Cleaning Cartridge filters),
saying I felt jubilant- was an understatement....
....BUT that's not the point, what I feel compelled to share with pool owners
who are looking for help on this thread, is
just as important as "turning" the "green" pool back to "blue", (as exhilarating as that is) just as critical
is figuring out what caused the algae outbreaks, In the First Place.....
Personally, after many mess ups,
giving me intimate knowledge of 'what not to do"...
Below is what I now know TO DO
1) Get a GOOD test kit (NOT talking strips although strips ok for general ranges) ... the SINGLE BEST thing I did for my pool water quality, was buying a home test kit, and learning to test my own water.
(vs running to the pool store for sometimes accurate but sometimes NOT accurate results) I bought the TF-100 test kit, but have also heard the taylor K2006 supposed to be excellent for accuracy as well.
This is my best advice from 11 years of mistakes....
1) TEST your water daily, in the summer, and even several times daily after the SLAM process if your pool is susceptible to algae re-blooms and/or high usage.
2) WATCH your pH Level. I have personally noticed FAR better results with preventing algae, when I am diligent to keep my pH at 7.5 or lower. In our pool, this is especially important because of the enormous vegetation-large trees and flower beds-surrounding 3/4 of our pool A lower pH allows the free chlorine to kill more effectively.
3) WATCH your CYA level. 30-50 is good, but lower is better than higher.
i.e., if my CYA gets over 50 ppm, I am careful NOT to add any additional tri-chlor or di-chlor to our pool, as they contain cyanuric acid (CYA binds with free chlorine making it less effective)
Happy swimming, and TEST TEST TEST if you find yourself continually fighting algae blooms....