RO/DI Chlorine (Free/Total) Hanna Instruments

[RussKubes]

Hello,

I wanted to double check that the filters in my RO system are doing a sufficient job of removing the Chloramine in my city water. I'm not sure how accurate the Hanna meters are, and thus how concerned I should be of the readings.

I used HI701 and HI711 for the tests. I ran the tests in order of DI, Tank, RO, Carbon Filters, then Tap Water. I thoroughly rinsed the vials with DI water between each test.

I was not concerned with the reported levels of Free Chlorine, but I am wondering if I should be concerned with the levels of Total Chlorine. I found it odd that it reported slightly more Total Chlorine in the DI water than the RO.

Last bit of info before I show numbers is the make up of my RO/DI system. It has a sediment filter, then Catalytic GAC, then a Chloraguard (Chloramine filter), then RO membrane, and finally two DI cartridges.

For the water in these tests, the TDS read between 1-8 PPM out of RO, and 0 PPM out of DI.

Source - Free Chlorine PPM / Total Chlorine PPM
Tap - 0.32 / 1.17
Carbon Filters - 0.00 / 0.05
RO - 0.00 / 0.04
DI - 0.00 / 0.07
Tank - 0.00 / 0.28

The tank is a 55 gallon, and has been running for at least a year now. Fish seem to be healthy. I do bi-weekly 20% water changes.

Any insight or feedback for these results would be greatly appreciated!

 

[RussKubes]

I'm not sure if there's been any other interest in this topic. I wanted to provide an update in case anyone else ever stumbles on it.

1) A few sources have reported that the Total Chlorine test is not accurate when you get down to very low levels (such as what's reported on the Carbon/RO/DI outputs).

2) Apparently Ammonia will show up on a Total Chlorine Test as a positive - even if it is not bonded with Chlorine.

3) The carbon blocks will break down Chloramine, remove the Chlorine, but leave most of the Ammonia.

4) It is suggested that my readings may just be Ammonia, but that should get removed by the DI.

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Ultimately since the levels are so low that I may attribute them to false readings, I will continue to monitor.

As a precautionary measure, I am adding NovAqua Plus to the tank as I do water changes.