What step am I missing when dosing based on the BRS calculator?

[New&no clue]

In my old tank, I dosed BRS 2-part based on their calculator and never had an issue. I've recently upgraded to a new tank and have been having a hard time. Did I do it wrong this time? Here is my process;

Step 1: test water night one

Step 2: test water again night two. The difference between night 1 and night 2 is the amount consumed in a day.

Step 3: calculate the water volume of the new tank. 180-gallon tank + two 34 gallon sumps = 248 water volume - equipment, rocks, and sand = total volume of 210.

Step 4: Imput data in BRS calculator

Step 5: dose that amount over the next 24 hours and test again night 3. If day 2 and day 3 are the same, the correct amount is being dosed to keep the parameters stable.

After following those steps on day 3, my alkalinity was the same. However, my Calcium had increased. Why did it work for Alk but not Calcium?

 

[Randy Holmes-Farley Verified Community Expert]

IMO, one day of depletion or dosing is not going to be accurately measured, especially with a calcium kit.

Stick with the dose you are using for a bit longer and watch to see how alk responds. If it is stills table, the dose of both si fine.

Only adjust the calcium after a week or more of monitoring. Its fine in the range of 400-550 ppm, so it takes a good while to fall out of OK ranges.