5 mL per 10 gallons is the same as 20 mL per 40 gallons and should have increased the Ca by 7 ppm. Since you measured a 30 ppm increase, there is an error or errors somewhere. My first guess is that the variation in the measurement of Ca is a likely source of the problem. Imprecise measurement of the dose is another. And your system is less than 40 gallons is another possible error.
Pretty close . His results bothered me too
They're bothering me too lol... Help me figure out how much water i have lol I'm over here killing myself trying to figure it out. Ok so i dosed dkh half strength and got .85 dkh up. It should be 1.06 dkh increase per 10 gallons at 5ml. How many gallons do ya think i got of actual water. About 25?