Spent the afternoon at wowens' house. Filter pressure 15 PSI with a few bubbles in visible through pump lid when I arrived, so first thing was backwash. Clean pressure 10 PSI.* Water is still just very "cloudy," not green, but you can only see maybe 8" below surface! She's been pulling water through vacuum at bottom of pool thinking there is a plethora of dead algae on the bottom of the pool from the mega dose of cal-hypo 75 by pool guy a few weeks ago. I suggested the pump was having difficulty completely priming via vacuum, since there were no bubbles at all within a few minutes of removing vacuum hose from skimmer, and that she may be better served just brushing for now until she can see the bottom--which may be a while.
Total of 10 lbs of CYA has been added since opening pool over a month ago. First 4 lbs added weeks ago. CYA test today showed near zero. (Water barely cloudy with full cylinder. Black dot still clearly visible.) Pool store measured at 20 ppm a few weeks ago (before wowens bought a test kit). Where did it go??? Anyway, added 6 lbs today, which
should put it around 30 ppm. That took pH down to 6.8, and TA to 80. Adjusted with borax and washing soda. Last reading of pH was 7.3 and TA was 120. No FC when I arrived. Added 2 gal.** 8.25% bleach. FC back to 0 in an hour! Continued to "SLAM" harder until FC maintained near 20 for a few hours (with no further additions), which is when I left. Pressure had gone from 10-14 PSI in about 8 hours. Told her to backwash at 15 and keep checking FC level. I told her rapid pressure rise was GOOD NEWS (evidence of filter clearing the water)!
Just got word that she had to leave abruptly. Upon returning, FC=13 and 16 PSI. She backwashed (pressure back to 10 PSI) and added 2 gal* bleach (which should raise FC to about 21 ppm) and went to bed. I reminded her to take another reading first thing in the morning!
A few questions:
1) Is 10 PSI normal for a clean filter? (See asterisk below.)
2) Did I steer her correctly regarding vacuum? (Save until water is clearer. Just brush for now.)
3) Why is water THICK cloudy (instead of green)? (Water is still about the same color as second picture in post #15 of this thread, even though it sat for a week with no circulation! New pump installed just 3 days ago.)
*10 PSI
seems low, but perhaps only because my clean pressure is 12.5 PSI. She has long been concerned that flow between skimmer and pump is restricted. Indeed, suction in hole at bottom of skimmer does not seem to be as strong as mine, but that is subjective and non-quantifiable. I told her even
if her suspicion is correct, she still appears to have
sufficient water flow, since the pump will prime and the flow at returns is strong.
**I am referring to the 121? oz jug as a gallon.