Dear sir -
I have downloaded and read your "The Complete Guide to Home Chlorination Systems". Thank you! This is an excellent guide. I have a water treatment system for iron that has a chlorine pump, retention tanks, a Big Blue filter, and a Culligan PE tank (a charcoal filter).
Question 1: I am now trying to calculate the correct chlorine solution for my system. The flow rate is 10gpm, Iron is 22ppm,and the chlorine pump rating is 12 gpd. As I understand your guide, the chlorine demand for iron alone would be 22. I am using the formula on page 12 of your guide. To solve for solution strength using a 50% pump meter setting (6 gallons per day), I calculated as follows: 10gpm flow x 22ppm chlorine demand x 1440 divided by 6 gpd pump meter = 52800 ppm chlorine solution. Have I done this correctly?
Question 2 - I am not sure if I calculated the chlorine demand correctly. I have two 120 gallon retention tanks, so with a flow rate of 10 gpm, I have a 24 minute retention time (correct?). How should I use this information to calculate the chlorine demand?"
Dear Colin - these are great questions. Here are the answers:
Question 1: For the formula, if you are using 5% chlorine bleach (which is the same thing as saying 50,000 PPM) you would use this:
10gpm flow x 22ppm chlorine demand x 1440 divided 50,000 = 6.3 Gallons per day of chlorine used
So say you have a metering that can pump 12 gallons per day, you would set the pump output to 50%
For Question 2, if you have a 120 gallon retention tank, and 10 GPM, then you have a 10 minute retention time, which is good. It doesn't really affect chlorine demand, other than making sure you have enough time to oxidize the iron etc.
Also see our online chlorinator calculator: