How to test for sodium tetraborate?

[waterbear]

Tetraborate will not lower the calcium level nor will they prevent scaling to the best of my knowledge. In a dose of 30-50 ppm and with the addition of acid to bring the pH back in line it will act as an algaestat and help buffer the pH. This is what products like Proteam Supreme and Bioguard Optimizer are. There are test kits and test strips that will test borate levels available from LaMotte and Aquacheck. Bioguard and Proteam dealers also can usually test for borates.
Adding 45 punds to a 15000 gal pool will put you in the ballpark of 30-50 ppm and will require the addition of 3-4 gallons of acid to keep the pH in line. It will add about 10 ppm to your total alkalinity. If you decide to add it to your pool the best way is to add 3/4 gallon (3 quarts) of acid and then immediately add 10-15 pounds of tetraborate until the entire amount of tetraborate is added. Wait 24 hours and adjust pH to about 7.4 with either acid if too high or more tetraborate if too low.

There are only 2 ways to lower the calcium...either drain and refill with softened water or use a sequesterant that has a high chelation ratio for calcium. These types of seqesterants are called 'Calcium Hardness Reducers' and will require maintenance doses on a regular basis just like sequesterants for other metals do. (Calcium IS a metal!)