Low pH and Low Alklinity

Since opening our pool this year, we’ve had a difficult time getting our pH and alkalinity at the correct level.  We’ve had our pool water tested at two different pool supply companies and both show a pH of 6.4 and Alkalinity of 40.  This is after we added 15 pounds of Alkalinity Up and 2 pounds of pH Up.  Could the pH in our pool be lower than the lowest scale on the test kit?  Although we had our pool covered this winter, there are drain holes along the center where rain and snow could filter down into the water.  Is it conceivable that we need to double the doses of the two chemicals?

What is your pool volume of water?

Our pool is 16 x 32 and has 20,000 gallons

If your current levels are still 6.4 pH and 40 Alk, you’ll need to add the same amount as was previously recommended. Test the water 24 hours later and see if the levels have increased. If they have not, try a different chemical brand. There is no reason that the levels shouldn’t increase.

Thank you for your input.  We added 5 pounds of alkalinity up and 2 cups of pH up and also dumped a bottle (I guess it was a quart) of phosphates decreaser on Friday.  We waited until this morning (Monday) and took another sample to the pool company.  Believe it or not, the pH and alkalinity still showed that the results were as low as before.  AND this was after using two different brands.  Today, following the fellow’s suggestion, I added another 15 pounds of alkalinity up and 2 cups of pH up.  I added the alkalinity in 5 pound increments.  When I went out to add the final 5 pounds, the water in the pool is now cloudy!  There is still an adequate amount of chlorine, so that isn’t the problem for the cloudiness.   If we hadn’t bought a new pool heater last year, I’d be tempted to have the whole thing filled with soil!