So when I opened my pool this spring, the water was clear with a lot of dead algae on the bottom. Was covered over winter with occasional addition of 3" chlorine tabs. Pumps winterized = no circulation for 6 months. Lots of clean rainwater added.
Vaccumed bottom with good result, which drained 25% of the water. Added tap water to normal level. Took water sample to Pool Store:
FAC > 5
TAC = unknown (they said they could not test it)
pH < 7 (my pH meter read 6.7)
TA = 100
CYA = 80
TDS = 500
CA Hardness = 120
I wanted to get the pH up first so they had me add 15lbs of soda ash. Nothing happened except a soapy/oily film developed on the surface. Skimmed off, it was greyish blue. No chlorine of any kind was added.
Repeat testing 2 weeks later showed the only change to be in:
TA = 130
(pH was still <7)
Nitrates = 10ppm
No further advice given.
Read the Pool School. I figured I had to stop using 3" tablets, superchorinate to get rid of the film, and aerated the water for 8 hours.
I am using an HTH test kit that only goes to 5 on total chlorine. Through serial dilution with distilled water, I calculate the total chlorine to be 20.
Now the water is clear, film is almost gone, and pH is "magically" up to 7.4 with no additional base added. Maybe superchlorination oxidized some organic weak acids?
Now the previous white bottom is greyish blue (actually quite pretty) and scrubbing does nothing.
I am concerned about the high total chlorine level and inability to measure free chlorine to guide my addition of bleach to ensure a safe pool for me and my dog (who drinks the water sometimes). I really just want to get the pool going to the point where my dog can do her physical therapy for a neurologic/orthopedic condition safely with me in the water if necessary.
What to do?
We are on a water meter and water is expensive here.
When pH is low and TA is normal/high why not just add a strong base like NaOH or KOH?
I could get a better test kit, with a wider range of chlorine measurement but am trying to save money (see below).
33,000gal, IG, circa 1970, (now) fiberglass over plaster, pac-fab paper cartridge, 1.5hp pump, polaris 280 (inoperable, UV damage) with booster, solar heat (inoperable, leak in powermat), skimmer (inoperable, line clogged & possibly fractured under concrete), main drain inoperable (long standing problem), jury rigged deep intake, skimmer line work-around in progress.