Observation on Chicago Water

[Cosmo]

I have a DI cartridge on my RO unit, and instead of running with mixed bed resins, I buy bulk Anion and Cation resin and load the cartridge with the top half Cation and the bottom half Anion. In the past several months I've been doing this, the Anion resin has always depleted long before the Cation started changing color.. John at Kent tech support said this could indicate a high level of positive charged silicates in the water..

Just last week, I noticed that the Cation is now depleting at either the same pace, or even a little faster than the Anion..

Don't know exactly what this means, but it does seem to indicate there has been a change in either the Lake Michigan source water, or how the city is purifying it before it goes out to the homes ???

My guess is the latter (duh) and since it corresponds to the change in seasons, I'm wondering what it is they might be doing, or adding, that's different ???

Just thought I'd post in case anyone might be interested or have a theory, or knowledge, of what might be causing this :-\

Jim

[RandalB]

It could also indicate that the way you are packing your resin in is causing the water to channel along the outside of the cartridge at the cation level to appear to deplete faster. BTW, don't go by color change when determining if your DI is depleted, TDS meter is the way to check.

The only thing Chicago does differently from season to season (Summer to Winter) is lower the chlorine levels and shut off the UV sterilizers.

You may be having a problem locally that's being treated by your water authority or may have damaged your RO membrane(s) as other thoughts.

RandalB <-- Still can't figure out why you're bothering with RO\DI with Chicago Tap water and no Reef Tank...

[Cosmo]

when I first bought the RO/DI I was buyng the "special" Kent HI-s cartridges that were essentially mixed bed on top and pure anion on the bottom 3 inchs or so... blue always went gold long before the mixed bed turned.

Thought of the membrane too, but I use a Hanna TDS meter religiously and haven't noticed any problems with any rise..

Packing the cartridge.. could be, but didn't do anything different than I have in the past but the results have changed ?

As far as why I still use the RO/DI... guess I'm just a :blockhead: on some things huh :funny: Actually, it's my mistrust of the city and my inordinate fear that they'll flush their system and kill all my fish .. the tap water does test fine for tds and ph so I agree that there's nothing wrong with it... most of the time :)

.. like I said a few weeks back though, once I get the drip in place, I'll have to use at least some waste water with the RO...

Jim