RO/DI Chlorine & Chloramine

[d2mini]

So typically I change my filters when TDS starts to show up. But I know we have high levels of chlorine and chloramine here in the Houston area and lately it's been even higher.
How do we know when a filter like this is exhausted?
@Bulk Reef Supply https://www.bulkreefsupply.com/brs-universal-carbon-block-filter-1-micron.html
I'm worried that my carbon block filters may be rendered useless well before any TDS starts showing.

 

[Flippers4pups]

Get these and I believe you test your waste water affluent. If it registers on the test strips, it's time to replace the carbon blocks.

Insta-Test Free & Total Chlorine & Chloramine Strips (Fresh Water)

Why does BRS recommend this? The easiest way to know if your city uses chlorine or chloramines is by using the LaMotte Test Strips for Free and Total Chlorine. Water Treatment facilities can change their treatment process without notice and usually change the amounts of disinfectants used...

www.bulkreefsupply.com

 

[JoshH]

Typically you can get a chlorine test kit similar to the ones they use for pools and test after the blocks but before the membrane. When replacing carbon blocks I take a look at there rated capacity in Gallons and keep track of how much I've made then replace them when I get around 8-90% of the rated capacity.

And you are right to worry as chlorine and chloramines won't show up as TDS so you wouldn't know they are spent by relying on a TDS meter.

 

[jwshiver]

I use the BRS Universal Carbon block that has a gallon rating before exhaustion of

• Chlorine 35,000 @ 1 GPM**
• Chloramines 3,500 @ 0.5 GPM***

I calculated out my normal usage to come up with a replacement schedule. For me that works out to a replacement of every three months on the conservative side. I added an event schedule in my Apex controller to remind when to order and replace.

 

[Randy Holmes-Farley Verified Community Expert]

Mine plugged with sediment and needed replacing before any chlorine or chloramine got through. As folks have noted, if you want to test, just get any cheapo chlorine kit (need not be for chloramine as it will show on a chlorine kit) and test both the tap water and the effluent (either from the DI, or with more difficulty but likely a bit better, after the carbon cartridge but before the membrane.

 

[Randy Holmes-Farley Verified Community Expert]

Typically you can get a chlorine test kit similar to the ones they use for pools and test after the blocks but before the membrane. When replacing carbon blocks I take a look at there rated capacity in Gallons and keep track of how much I've made then replace them when I get around 8-90% of the rated capacity.

And you are right to worry as chlorine and chloramines won't show up as TDS so you wouldn't know they are spent by relying on a TDS meter.

To clarify a bit, chlorine in tap water is typically present as hypochlorite (unless the water is very acidic), and will show on a tds meter, but will be reduced by the membrane, removed by the DI, and even if not, is usually very low to begin with so wouldn't show much more than 1 ppm TDS or so.

 

[JoshH]

To clarify a bit, chlorine in tap water is typically present as hypochlorite (unless the water is very acidic), and will show on a tds meter, but will be reduced by the membrane, removed by the DI, and even if not, is usually very low to begin with so wouldn't show much more than 1 ppm TDS or so.

Thanks for the finer details Randy, I was mostly pointing out it wouldn't be a noticeable change that someone would flag as unusual and a reason to change out there carbon blocks. I guess I was a little fast and loose with the not showing up wording lol.

 

[Randy Holmes-Farley Verified Community Expert]

Thanks for the finer details Randy, I was mostly pointing out it wouldn't be a noticeable change that someone would flag as unusual and a reason to change out there carbon blocks. I guess I was a little fast and loose with the not showing up wording lol.

Yes, I agree, it is certainly true that TDS is not a useful guide. .

 

[d2mini]

So am I understanding correctly that I would test the waste water? I do have pool test strips that I use for our pool.

 

[Flippers4pups]

So am I understanding correctly that I would test the waste water? I do have pool test strips that I use for our pool.

Yes. Free and total test strips.

 

[Randy Holmes-Farley Verified Community Expert]

So am I understanding correctly that I would test the waste water? I do have pool test strips that I use for our pool.

Yes, that would be fine.

 

[Opus]

Not sure how many carbon filters you are using. If you are using 2 of them, then maybe you should look at replacing one of them that is specifically made to remove chloramines. Normal carbon blocks will remove them but the ones made to do it specifically are more efficient and will last longer.
On a side note, chlorine will destroy your RO membrane but chloramines will not, at least, not in the amounts we will see.