Testing RODI Carbon Block

[AquaKey]

Is it possible to test the reject water of RODI with a typical OTO reagent (the cheap reagent used in pool test kits) for the presence of chlorine and chloramines? Don't really care much about it's value, really just trying to see when I need to replace the carbon block.

 

[blaxsun]

Just replace the carbon every six months (max).

 

[AquaKey]

I get that, more interested in understanding the chemistry of whether it's feasible.

 

[Malcontent]

Its lack of low range sensitivity might be an issue. Low levels of chlorine can harm fish or your RO membrane (given enough time).

 

[Randy Holmes-Farley Verified Community Expert]

Yes, it is feasible to do what you are suggesting.

 

[spsick]

BRS sells cheap pool strips which give you a rough idea. Hach CN70 if you really want accurate results to dial in replacement interval. I found I have to replace my first carbon block every 2 months or I get blow by.

 

[AquaKey]

I can confirm it works. Vial on the right is waste water, left is rodi water. It might be hard to see in the pic, more noticeable in person. Definitely requires a control because the indicator at such low ppm is hard to tell without a control. Tap water also had a slight yellow tint too.