Bleachcalc units

[shadowman]

I suppose this has been covered many times before but I need to make sure I understand the bleach calculator. When you set the units to Imperial, does that mean I have to convert the gallons to US standards. I didn't notice it at first so I wonder if I have been using too little bleach.

Thanks!

[CarlD]

I suppose this has been covered many times before but I need to make sure I understand the bleach calculator. When you set the units to Imperial, does that mean I have to convert the gallons to US standards. I didn't notice it at first so I wonder if I have been using too little bleach.

Thanks!

The simplest answer is to keep your units consistent, whether you use the bleach calculator, the formula (I'll put it in later) or The Rule of Thumb. If you use the same units to measure bleach that you use to measure pool volume, they all work. So if you use Imperial Gallons, use it for the bleach and the pool volume. If you use liters, it works too, and also (for most of us) US gallons. So if your water is in US Gallons, then convert bleach to US gallons (128 ounces to a gallon).

The Formula:
(1,000,000/PV) * C * UB = FC ppm Added
Where--
PV is Pool Volume in gallons or liters
C is the concentration of the bleach, converted from percent to decimal (5.25% becomes .0525)
UB is the units of bleach (must be same units as PV)
FC is Free Chlorine added
1,000,000 is because we are computing Parts Per Million.

This leads to the rule of thumb: If PV is 10,000 gallons (or liters) and UB is 1 gallon (or liter) then the concentration left as a percent = FC

So adding one gallon of 5.25% bleach to 10,000 gallons adds EXACTLY 5.25ppm! Cool, huh?

I have about 20,000 gallons, so I need 2 gallons to get 5.25ppm. If I use 6%, I need 2 gallons to add 6ppm!

You can figure it in your head!