Photo report
Thursday, July 16
- Serviced by
- Austin Andrews
- Pool
- Backyard pool
- On site
- 41 min
Photos from the visit
Before the work
How it was left
What this visit found
Salt cell is reading low and needs a clean
Keeping an eye on itCell output is down and the plates have scale on them. It will still run, but it is working harder than it should and the chlorine will keep drifting low until it is cleaned. Not urgent this week. Worth doing before August.
The water
- Clarity
- Clear
- Water level
- Normal
- Filter pressure
- 18 PSI, 6 over clean
Free chlorine
2.4 ppmIn rangeIdeal 1 to 4 ppm
The chlorine still available to kill anything that lands in the water. This is the one that keeps the pool safe to swim in.
Total chlorine
2.6 ppmFree chlorine plus the chlorine that has already been used up. When it runs well above free chlorine, the pool needs shocking.
pH
7.9HighIdeal 7.2 to 7.8
How acidic or basic the water is. Off in either direction and the chlorine stops working properly, eyes sting, and the plaster or the equipment starts paying for it.
Total alkalinity
90 ppmIn rangeIdeal 60 to 100 ppm
The water's resistance to pH swings. Get this right and pH mostly holds itself steady between visits.
Calcium hardness
340 ppmIn rangeIdeal 200 to 400 ppm
Dissolved calcium. Too little and the water pulls it out of the plaster; too much and it deposits as scale on the tile and inside the heater.
Cyanuric acid
55 ppmLowIdeal 60 to 80 ppm
Stabilizer. It shields chlorine from the sun, which a Texas summer makes essential, but past about 80 ppm it holds onto the chlorine so tightly that the chlorine stops working.
Salt
3100 ppmIn rangeIdeal 2700 to 3900 ppm
What the salt cell makes chlorine from. Too low and the cell cannot keep up; too high and it corrodes the hardware around it.
Water temperature
88 °FWarm water burns through chlorine faster and scales more readily, so the targets shift with the season.
- Minimum chlorine for this pool
- 4.1 ppm
- Combined chlorine
- 0.2 ppm
- Water balance (Langelier index)
- +0.53scaling
Stabilizer holds onto chlorine, so the floor rises with it. At 55 ppm of stabilizer, anything under this is not sanitizing regardless of what the strip says.
Below the 0.5 ppm shock threshold. The chlorine in this pool is doing its job rather than sitting used up.
The water is holding more calcium than it can keep dissolved, so it will deposit as scale on the tile line and inside the heater. Balanced is anything between -0.3 and +0.3.
What went in the water
Muriatic acid
pH at 7.9, bringing it back toward 7.6
24 fl oz (about 3 cups)
Stabilizer
Stabilizer had drifted down with the summer rain
1.5 oz
What was done
Cleaning
- Skimmed surface
- Brushed walls and steps
- Vacuumed
- Emptied skimmer baskets
- Emptied pump basket
- Cleaned tile line
Chemistry
- Tested water
- Balanced chemicals
Equipment
- Checked equipment
- Checked filter pressure
- Inspected salt cell
- Checked water level


