Carbon filter to block chlorine from RO

I picked up a used EZ Pure ro/di system and decided I wanted to change the carbon block after I used it for 6 months just to be on the safe side. Not liking the weight of this thing or the price of a stock replacement ($150) I bought a 4x20 housing and carbon filter. Now its much lighter and I can replace the filter for a few bucks down the road.

I decided to cut open the old carbon filter and discovered it was FULL of bulk carbon. I’m guessing it has over 100 times as much carbon as the little paper/carbon filter I replaced it with. Now I’m wondering if it could have lasted many more years and if my replacement, while cheaper, is insufficient.

Can anybody shine any light on this? Is there anyway to detect chlorine getting past the carbon so I don’t have to guess when to replace? Is there anyway to make a bulk carbon filter that is refillable?

Does it really matter. I always change filters,fluids parts way before needed at what the equipment cost (which is a lot) is it really worth it to try to extend a carbon filter and extra week or 2 months just to mess up more expensive ro’s. Plus what that equipment makes u per hour. When I’m wfp I’m at about $225 to $250 an hour. I had part break off took 3 hours to find something that worked in its place. Less than a $5 dollar part cost me $675 of my time that I could have been making money. Now I have 5 extra of everything weather I need it or not or will ever use it or not, if something goes I have it and can can it or replace and get back to making money. $150 carbon filter is nothing, I would have 2 extra in my truck at all times and change them out way before recommended. In the long run you will always make more money that way.

I get your point about redundancy, but yes…having correct information about service intervals and investing in the right tools for my business matters.

I have the same system and I just a chlorine tester at the R/O flushing valve.

Do you have a link to the chlorine tester you use? My pool supplier told me the ones he sells wouldn’t reliably detect chlorine in tap water before a carbon block, so they’re useless after one.

Does anybody know if chloramines damage RO’s, or if its just chlorine we need to filter out?

I understand that many local government switched from chlorine only, to chloramines for potable water as it stays effective in the water much longer.
So, there are two kinds of chloramines - the ones used to sterilise your tap water are ‘chlorine and ammonia’ - and yes, my understanding is that they are potentially damaging to an RO.

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So, PerryTait, is a carbon filter the best way to protect RO filters from areas with high chlorine or chloramine levels? Are there any other steps that can be taken?

Activated Carbon is the product that is the most commonly used - it is crushed quite small to increase the surface area with the water as it passes, especially with a smaller filter - we simply use a 2.5" x 10" with the Wash-iT PRO - two for 12 bucks at Home Depot if you want…

The USA does not really use a lot of chlorine / chloramine compared to some other countries - usually below 2ppm - but there is a recommendation for it to increase to 4ppm.

The beauty of a $6 filter is you can schedule to replace it - 1st of each month… Done. With an 8 month season, that’s under $50 to protect the membrane.

You can do the same with the DI RESIN for your Ezy Pure - 20" of resin, refillable cylinder - you’re saving big bucks.

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Perry, I found this video of some testing of standard pleated carbon blocks vs. bulk carbon blocks vs specially treated chloramine/chlorine carbon blocks. If chloramines damage RO, and if these tests are accurate, we may need to rethink our filter as the standard carbon blocks completed failed at removing chloramines after what might be a single days use, though its hard to compare window cleaning usage to aquarium/reef usage.


I found some information that it actually takes 10 minutes of continued circulation through a carbon filter particularly a catalytic carbon filter to effectively remove chloramine. That means you would have to have a buffer tank of de-chlorinated/chloriminated water that has gone through at least 10 minutes of filtration before it goes through the RO’s.