I tasted it right away from the hydrometer jar. So…I stuck my head into the mostly empty bucket I’d just kegged from. Wow…That up the nose no doubt chlorine smell. Hard to believe it could get that bad when I carbon filtered…
Results are in, view link below. I put on my actual scientist hat for this one because 1) I was extremely curious about this issue, and 2) I am surprised by the results.
In case you don’t want to read the write up, the punchline is that yes, heating to strike temp does remove all the chlorine. An overnight stand does not.
Cool! Nice work.
“Weather effects” = too much rain and they dumped raw sewage into the lake. Much of the summer, the beaches are closed because of too much ecoli. Good times.
I rarely use campden and have not had a problem with Chicago water. I do filter it and maybe the heating to strike temp drives off whatever is left.
Campden is cheap insurance though. Probably should use it more often.
Interesting. Thank you for sharing. Well done.
What was the flow rate through that carbon filter? If it was greater than 1 gal/min, the chlorine passed right through.
To give you an idea of how slow the flow needs to be, putting a plug with a 1/16" hole in the water line on the carbon filter will reduce the flow rate to about 1 gal/min under typical water pressure.
If the water has any chloramines, then the carbon filter is useless unless the flow rate is under 1/10 gal/min.
How does the size of the filter, and type of media affect this flow rate?
I just installed a 12"x52" Vortech tank with 2.0 cu-ft of catalytic carbon. They say 5gpm would result in excellent reduction of chloramine. The faucet doesn’t flow that fast though.
What flow rate should I run this at for brewing water?
Is the 0.1gpm recommendation for typical 10" or 20" block filters?
The size of the filter affects flow rate as presented in the following equation: The volume of MEDIA (cubic feet) in the filter unit divided by the flow rate (cubic feet per minute), is known as the Empty Bed Contact Time (minutes). To effectively remove chlorine (aka: hypochlorite), the contact time needs to be at least 2/3 minute. To effectively remove any of the chloramine compounds, the contact time needs to be at least 6 minutes. For the typical 10-inch carbon filter unit, that equates to needing the 1 and 0.1 gpm flow rates that I mentioned above. For the big carbon tank that you mention, that flow rate can be assessed by reconfiguring the formula above. Its obviously a much higher flow rate.
Loose or granular activated carbon (GAC) is less dense than the more modern carbon blocks that are now available to consumers for the 10- and 20-inch filter canisters. Therefore, carbon blocks are now preferred over GAC filters.
Media volume/flow rate=contact time
2.0 / flow rate = 6 minutes
flow rate = 12 minutes minimum
My tank head says it has a restrictor installed for 10gpm max flow rate. If I use a 5gpm laminar restrictor at the kettle, would it be safe to assume enough/all chloramine is effectively reduced below the chlorophenol danger zone?
Nope.
2 cu ft is about 15 gallons.
15gal / 6 min is 2.5 gpm If the flow is restricted to 2.5 gpm, then you should remove all chloramines. For all others on this post, recognize that 2 cubic feet of activated carbon is A LOT.
Martin,
Thanks for the explanation here, and the formula for contact time. But I realize there may be something missing. What about the life of the carbon block filter? How does time in service affect its capacity to remove chlorine/ chloramine? I use a 10" Pentek EP-10 cartridge which is installed in line on the cold side of my kitchen supply, so running all my cooking and beverage water as well as water for brewing purposes (including immersion chiller, maybe my biggest single requirement!) I generally replace it every 3 months as a matter of course. Will my required contact time change over time?
Rob, I hoping that you’re monitoring the residual total chlorine in your filtered water in order to help you assess when the carbon cartridge is exhausted. That’s the way we do it for our industrial clients. It’s so important that there are automated monitoring equipment that constantly test that the filtered water chlorine compound concentrations are below limit. Of course that’s unreasonable for a homeowner, but you can perform occassional tests with a simple swimming pool test kit to confirm if and when there is chlorine breakthrough.
I use those EP-10 carbon filters in my RO system also and they are good. They are carbon block style and they do last. The treatment mechanism between activated carbon and chlorine compounds does ‘consume’ the carbon material. Eventually, the carbon will be used up and it must be replaced. The Pentek site does state that this filter will remove the FREE chlorine in up to 6000 gallons of water at 1 gpm. Be aware that FREE means chlorine or hypochlorite. It specifically excludes the BOUND chlorine species such as chloramines. If your water supply has chloramines, then the 1 gpm criteria goes out the door. Then to get the desired chloramine removal, the flow rate has to be reduced to under 0.1 gpm. But the amount of water that the filter can treat should still remain consistent (6000 gal).
Understand that filter and system providers are going to provide conservative estimates of capacity and performance in this case since it means that they are going to sell more filter replacements. If you’re interested in maximizing your dollars, you’ll be testing and monitoring the performance of your system to assess when you really need to perform those replacements.
Thanks, I’ll pick up a chlorine test kit and see if I can save money. I’ve just been replacing them at a very conservative interval.
The other thing that a Total Chlorine test kit can tell you, is if your flow rate is too high and full removal is not achieved (aka: chlorine breakthrough).
Remember that a garden hose can easily deliver about 5 gpm. A sink faucet could also come close to that. In either case, the flowrate far exceeds the 1 gpm rate that a standard 10 inch filter can treat for chlorine compounds. Putting a restrictor with a 1/16-inch diameter hole on the line will bring the flowrate down around the 1 gpm rate.
I ordered a total/free chlorine test kit from Hach. Hope that’s a good product.
Since you mentioned flow rate here on the forum some time ago, I’ve also been erring on the side of caution and throttling the faucet way back. I’m running well below 1 gpm, probably more like a quart a minute. It will be interesting to dial this in with actual measurement. That said, I’ve never had a problem with chlorophenol anyway, even with less careful filtration.
hmm… OK
Does this rate apply only to regular activated carbon ?
I’m using Calgon Centaur Catalytic Carbon, it’s claimed to have improved efficiency over regular GAC.
The enhanced carbon products do help with chloramine removal, but the throughput isn’t enhanced that much.
I understand. Thank you, sir
Ok, thought of another question or two. I should have my test kit in time to either replace my filter or not before this weekend’s brew. I’m not sure what the resolution of the test is. But:
While I realize our goal for total chlorine in brewing water is zero, is there an acceptable minimal level, say a hair above zero, that can be relied upon to gas off as the liquor is being heated? Further, does it depend upon whether chlorine or chloramine is used? AFAIK my city only uses chlorine (according to their public information) but is there a way to confirm this based on the ratio of free to total chlorine? (Apologies if I could have just looked this up in Palmer and Kaminski. I’m lazy and anyway the answers may be of interest to others. )
Do read the Water Knowledge page of the Bru’n Water website and you’ll see the discussion of the incredibly low threshold for chlorophenol creation and perception. Virtually 100% removal is needed prior to brewing usage.