RODI Carbon block replacement - measure chlorine?

[Linwood]

The general advice I see is to replace the carbon block every 6 months, however, these are definitely usage based filter, and (a) it's hard to know how much usage I have, and (b) on the original filters I have no idea what they are rated for.

Telling if they are clogged is easy - I have pressure gauges on both sides of the collective (sediment + 2 carbon), and after about 6 months the drop is only about 5psi max (flushing state). So there's plenty of particle collection space left.

But the carbon's chlorine capacity is the other concern.

Anyone know whether there is any point in measuring its chlorine neutralization as a means to know when to replace? What would be normal, and what would be the replacement point? (And what kind of test kit can test that level)?

I have spares, it's not that... I just hate to consume things that are still working perfectly. But I also don't want to damage the membrane.

 

[militantpotato]

A total dissolved solids meter would tell ya if anything is getting by.

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[Linwood]

Well, only after the damage is done to the membrane by chlorine.

I think from lack of finding info there must not be a good way to evaluate the carbon filters, at least economically.

 

[militantpotato]

There are lots of reagentless online free chlorine monitors, though unless I'm missing a consumer grade one they start around $3000.
Would teeing off the line prior to the membrane for regular testing be feasible?

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[Linwood]

There are lots of reagentless online free chlorine monitors, though unless I'm missing a consumer grade one they start around $3000.
Would teeing off the line prior to the membrane for regular testing be feasible?

Well, yes, plus the waste line is already exactly that -- that's why I thought this was easy, just put a test tube under the waste and check chlorine - if it's detectable, time to change the carbon blocks.

But the pool tests, at least to my read, are aimed too high to be useful, so I think this is not very viable. By the time you start seeing 0.5ppm +/- I suspect the membrane is toast.

 

[militantpotato]

There are higher resolution test strips, Grainger has a couple.
http://m.grainger.com/mobile/produc...-Strips-WP70513/_/N-kr6Z1z0a583?fromPidp=true

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