How much chloine should be in my holding tank?

[CountryBumkin]

Recently I had my water softener and carbon filter tanks rebeded. The guy doing the work said I should be reading some chlorine in the large holding tank - but nothing showing on the water test (Pool chlorine test kit).

I had this system installed 20 years ago and the only instruction I got then was to add one gallon of bleach (6% I think) to the Chlorine tank when it is low. He never mentioned checking the level in the large holding tank.

However, the new Water Service company (the original water guy retired) said I should add 2.5 gallons of the stronger chlorine (get it at Pool Supply store) rather than what I have been doing. And I should see a trace amount of chlorine in the holding tank.

To be honest, I may have misunderstood the instructions form the installer, 20 years ago, and I have no instructions on how much chlorine I should be using, but the water seemed fine.

The reason I had the new company come out and rebed, is because I'm now smelling sulfur - and the last rebed was ten years ago.
Testing at the top of the holding tank (see photo) shows zero chlorine in tank (also, does it matter if I test at the top or bottom hose bib on the tank?

So what is the proper amount of chlorine to add the Chlorine tank (its a 25 gallon tank). The injection pump is set at mid point ("5").

 

[CountryBumkin]

I just wanted to add - the Chlorine injection pump is new and working fine - the tank level drops normally after days of use. I think it is about a month (or two) before the 35-gallon chlorine tank is low enough that I need to add more chlorine/water to it.
I turned it up the chlorine pump to maximum (setting 10) for now and I also ran the pump for about 4 hours straight and still see no chlorine in the large tank. Maybe I need to run it longer.

 

[Sponsor]

 

[Valveman]

Moving to Softener Forum where you may get more help with this.

 

[Reach4]

What are those things atop the PVC pipe that feeds your chlorine test point?

How do you blow the sediment out of your contact/settling tank?

 

[Bannerman]

UV light & heat will reduce the time for the chlorine solution to become weaker until finally neutralized.

Because your large chlorine solution tank is translucent and is located outdoors, suggest protecting the tank to reduce UV exposure. Since your tank is located in a usually warm location, suggest also reducing the quantity of prepared solution so as to cause you to prepare sufficient fresh solution every 2-weeks.

 

[Bannerman]

Sufficient chlorine will oxidize iron, manganese and sulfur to convert them from a ferrous state (dissolved in the water) to a ferric state whereby they will become unsuspended and will precipitate out or maybe filtered out as solids.

Your contact tank will contain no media but the slower upward flow across the large diameter tank will increase the contact time for the chlorine to convert the iron, manganese or sulfur, and allow the resulting solids to precipitate out and collect on the bottom of the tank, while allowing the 'cleaner' water to exit from the top of the tank.

As R4 mentioned, your contact tank should be periodically "blown-off" using the valve at the bottom, to flush out the accumulated solids from the bottom of the tank. Suggest removing the existing globe style boiler valve and replacing with a full port ball valve to increase the drain flow rate so as to more thoroughly eliminate accumulated solid debris.

When there is iron, manganese or sulfur present, the chlorine will become less effective as it weakens while acting on the I, M or S. Obtaining a water sample from between the contact tank and the carbon tank, will allow you to determine if there is sufficient residual chlorine present in the water exiting the contact tank. When there is too little chlorine remaining in the water exiting the contact tank, that suggests there may continue to be I, M or S remaining in the water, and therefore an insufficient quantity of chlorine being injected for the quantity of I, M or S that is present in the raw well water.

Any residual chlorine present after the contact tank, is to be removed by the carbon filter along with reduction/removal of harmful bi-products of chlorination and other chemical contaminants.

Because carbon will continue to effectively remove chlorine long after it's capacity to remove other contaminants has been depleted, suggest replacing the carbon media more frequently than every 10-years. Assuming your carbon filter contains 1.5 ft3 carbon in a 10" X 54" tank, the usual recommended media replacement frequency is 5-6 years, and 6-7 years for a 12" tank containing 2 ft3 of carbon media.