With the use of a regular retention tank, chlorine requires a minimum of 20 minutes contact time and 30 minutes is a better goal.
Chlorine is heavier than water and while setting in water will fall to the bottom of a solution tank unless the solution is constantly being stirred/mixed 24/7. Without stirring/mixing the solution tank pickup tube will be picking up the strongest chlorine solution from the bottom of the tank and the solution being used/injected will constantly be reducing in strength until the next time new solution is added to the solution tank.
That makes proper retention time more critical and why maintaining a free chlorine residual of .2 to 1.5 ppm is a must. Free chlorine is different than total chlorine. The free chlorine should be tested after the retention tank and not from the bottom of a retention tank.
Pressure tanks of any kind should not be used for chlorine retention.
The best retention tank I've ever seen... I sold a lot of them over many years with only two problems; one an owner broken bottom drain elbow and a broken during shipment distributor tube.
Both of those are good links. I like fiberglass or plastic tanks instead of metal when using chlorine.
A captive air or hydro-pneumatic pressure tank needs 75% to 80% air. A retention tank has no air in it. So a 100 gallon pressure tank only holds 25 gallons of water, where a 100 gallon retention tank holds 100 gallons of water. Both have to be capable of handling pressure, but without any air, the retention tank won’t give any drawdown. Using a 100 gallon retention tank in front of a 100 gallon pressure tank would actually give you about 125 gallons of retention space.
Like I said earlier, I have used a CSV and a 4 gallon pressure tank with a variable flow chlorinator. I just used enough 12” pipe to hold about 100 gallons of water before I reduced it back down to 1 ¼” pipe and went into the house. That way my retention “tank/pipe” is underground and didn’t take up any room in the pump house.
Any opinion, good or bad on the CT-80? Many of our customers use it, and the new design is a huge improvement for the connections. I have not heard any complaints, but any feedback would be appreciated.
Nothing else you'd use chlorine for would do that.
This discussion is educational...
Help me to understand this:
Regarding the chlorine injector, when running on a standard system (non-CSV). Doesn't the flow rate vary in a standard pump/pressure-tank system, depending on the pressure developing as the tank reaches 'full'?
IOW doesn't a 12GPM pump perhaps start out in its ON cycle at 12GPM flow and, as the PSI of the system increases, slow to some lower GPM?
In which case the chlorine injector needs to be adjusted to the average GPM between start and stop?
In that case how do we know the actual GPM in order to set the chlorine injector correctly?
Ja, pump GPM runs on a curve, so you just SWAG it. The pump curve can vary also with changing water levels.
It's good to know at what point to test the free chlorine. I made the mistake of testing after the carbon filter.
I have tested immediately after the contact tank, and it's 'off the scale'; my scale only goes to 3ppm.
The feed-pump that was installed is adjustable, but I've adjusted it to the minimum, and I've diluted the solution to 1:6.
According to my calculations, pumping @ 5.4GPM, with the Stingray feeder set at the minimum or approx. 10gal/day, the water going into the contact tank is @ 11ppm chlorine.
Should I simply continue trying lower concentrations, using trial and error, to obtain the lower free-chlorine ppm needed coming out of the contact tank?
Last edited by hcw3; 04-04-2012 at 07:56 PM.
Continue to lower your concentrations. A gallon of chlorox bleach is 65000 PPM.
Without a CSV the pump performs according to the curve. So a 10 GPM pump might start out pumping 12 GPM at 40 PSI, and by the time it shuts off at 60 PSI will be down to 10 GPM flow. So that is an average of 11 GPM as far as your injector pump is concerned.
[B]No, plumbing ain't rocket science. Unlike rocket science, plumbing requires a license[B]
Ok, that figures. Thanks.
About this Chemilizer injection pump that ditttohead mentioned...
Has anyone here got any experience with the Chemilizer? In their docs they suggest that the injector needs to be installed before the pressure switch. I'd like to have a branch coming off the line before the injector, to connect my non-chlorinated garden-hose, and it would be tidier to install it all after the pressure tank.
Another question, the Chemilizer is installed with 3/4" hose connections. I have 1" pipe from the pressure tank, which goes all the way through the softener system. Will reducing to 3/4", and then expanding back to 1" here at the injector, cause problems with noise or otherwise? Does this kind of 'compression and decompression' make trouble?
Thanks for all the help with this guys, it sure is nice to have knowledgeable input, trying to get this system right.