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Anonymous

Guest
Hey,

I recently bought a RO/DI unit and now I am getting silicate in the pure water. Does the DI section need a recharge or replacement some time? It's been making water for my 75g for about 2 months.

-Nathan
 
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Anonymous

Guest
Hi Nathan,

Most RO/DI units I have seen and worked with do not allow you to regenerate the DI, you have to replace the "cartridge". What do you mean by silicate? It does not sound like the DI is causing this problem, but maybe the carbon/prefilters are clogged and allowing materials to get thru the filter. How much water has the unit processed? The amount of water the DI can process depends on what is in your water. The more dissolved material in your tap water, the quicker the DI will need to be replaced.

Good luck!
 
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Anonymous

Guest
Actually yes the dark part has mostly changed to orange. I suppose this means that the resin has lost most of it's usefullness.

I have produced perhaps 200-300g of water. Is that normal to have to replace the DI cartrige so soon? Perhaps my city water is really filthy...

-Nathan
 
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Anonymous

Guest
Hi Nathan,
Most DI filters change color when they are depleated.Is yours in a clear canister?If it is you should see a color change.The Kent Marine DI filter changes from a purple/red to a light brown color when exhausted.The color change starts from one of the filter and slowly goes to the other.The DI section does need to be changed when exhausted or you will get some phosphates and silicates in your pure water.Kent does sell Hi Silicate di cartriges.Are you sure you have silicate in your water?The di should last a lot longer then 2 months unless your tap water is very bad.Mine lasted 6 months with me useing 25 gal per week.HTH,Bob

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Anonymous

Guest
Just for reference, most ion exchange resins can indeed be recharged by soaking them in a concentrated chemical bath. Although this is certainly not recommended for the home user, it definitely can be done if you know what you're doing. For example, cation exchange resins are simply flooded with a strong acid to displace the bound cations.

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Anonymous

Guest
Nathan,

There is no real normal time frame in which a DI cartridge will last. For example, I personally know people who've gotten over 1000 gallons out of a quality DI, then there is me, who gets only 100 gallons. My source water is laden with high CO2,which passes right through an RO unit and is gobbled up by the DI.
I've never been a fan of the color change DI's since exhaustion is subjective. Spectrapure units often come with Electronic Purity monitors which measure the conductivity of the water. Conductivity is directly related to the # of ions in the water. "Pure" water, (H20, and that's it) has 0 conductivity. I run a double DI system after my RO so that if I fail to catch the exhausted DI cartridge, my second cartridge catches any waste products. I can produce water of "0" conductivity using this method.
FWIW, once a DI is exhausted, it will quickly release the most weakly chemically bound ions, which just happen to be Silicates and Phosphates !!

I hope this helps.

John
 


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