MY SUGGESTIONS
Learn more yourself about looking after your pool, don't rely on the "Free Water Tests" from the pool shop unless you have them do the test & then take the results home & check them against the following:
Langlier Index Chart Table Representation yourself.

It is not hard to read the chart & using the accompanying dosage charts, You can decide for yourself if & what chemicals are needed.

INSTRUCTIONS:

I have given options for balanced water at two pH levels, 7.5 & 7.7 this is because the 7.5 is the optimum level & the 7.7 is the best obtainable level which some people can hold in hard water areas & areas effected by wind blown High pH pollutants. If you have a Total Alkalinity of 70ppm & a pH of 7.5 then the optimum Calcium Hardness level for your pool is 375ppm. If your pH is 7.7 the the optimum CH level is 240ppm. These tables can be used in reverse as many times the Calcium Hardness level is controlled by the makeup water. If your CH level is 500 & you can hold your pH at only 7.7 then keep your TA down to 50ppm.

GO TO END OF CHART FOR MORE NOTES.

SATURATION  INDEX / WATER BALANCE CALCULATOR                         Temp 1 Cal 2 ALK 3 pH 4     F Tf * ppm Cf * ppm Af * pHf *     32 0.0 25 1.0 25 1.4 7.0     37 0.1 50 1.3 50 1.7 7.1     46 0.2 75 1.5 75 1.9 7.2     53 0.3 100 1.6 100 2.0 7.3     60 0.4 125 1.7 125 2.1 7.4     66 0.5 150 1.8 150 2.2 7.5     76 0.6 200 1.9 200 2.3 7.6     84 0.7 250 2.0 250 2.4 7.7     94 0.8 300 2.1 300 2.5 7.8     105 0.9 400 2.2 400 2.6 7.9       0.70   2.2   2.0 7.0     TDS 5 -1000 TDSf-12.1 -12.2 TDSf-12.2 1000             Saturation Index Factor = -0.30                                                 1   Tf  *     =   Temperature factor     Saturation Index formula      2   Cf  *     =   Calcium factor     SI= Tf + Cf + Af + pHf - TDSf        3   Af *     =    Alkalinity factor     or        4   pHf *   =    pH factor   1+2+3+4-5 = Sturation index Factor        5  TDSf * =    Total disolved solids                                                                         -0.30           -0.4 -0.3 -0.2 -0.1 0 0.1 0.2 0.3 0.4   Corrosion                                                       Balanced Water Scale Scaling                                                     This is a simple calculator for water balance. In the bright Yellow box's                 enter the corresponding factor number. Then look at the blue box for                  your calculated results. Now reference the balanced water scale.                  you are within the -0.3 to +.03 range you are in balance. If you are                 not. Contact me or your pool professional for corrections. There may                 be variables you need to discuss. Just because your pool is clean and                     clear does not mean its balanced. If your out of balance you are leaving                     yourself open for future problems. Maintain your investment.