I set up intex 18 x 9 approx 4500 gallons. Added salt(120 LBS) and CYA( 1/2 GALLON LIQUID). Tested CYA about a week into setup. It was a little low. Added about 8 oz more CYA. Now I read it yesterday, Its not reading at all? I'm using the TF-100. Could heat of the day affect the reading its like 114 degrees out side pool water is like 102.