808jaymakoa
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I'm new to RO/ di and have been filling my new tank. I'm about 75 gallons in. But the top chamber of the unit is starting to turn a burnt orange. Is this normal or do I need to change it already.
Help with RO/DI unit
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redfishbluefish
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Interesting DI cartridge....haven't seen one like that. Although I've never seen that particular color change, you have a color-changing DI resin. As it "exchanges," it changes color. I personally do NOT use the color change to determine when it is completely spent. I rely on an in-line TDS meter to tell me it needs to be re-generated. You still have a ways to go before that one is "done."
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808jaymakoa
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Alright good to know. I was hoping I didn't need to change the resin this soon. I just got this thing. Thanks
The only way to know is with a TDS meter. A good handheld TDS meter is only $20-$25 and worth their weight in gold. I have two dual inlines and never even turn them on, they lack accuracy, are not temperature compensated and are limited to two places. To test a RO/DI you need to know at least 3 TDS readings, tap water, RO only and final RO/DI. You will also want to know your ATO TDS, stored water for changes TDS and more so the inline is very limited. If the resin has changed from its original colore it probably past its useful life and now is adding stored TDS back to the finished water. Some things like phosphates, silicates and nitrates are weakly ionized and get released by the resin even beofe it is exhausted, the ONLY way to know is to test the TDS, color changing resin is very unreliable. I would also take the DI off the top of your syste and mount it vertically like the other filters and allow it to fill from the bottom and exit the top so all reain and wate rcome into contact with each other rather than channeling or short circuiting when horizontal.
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808jaymakoa
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Thanks for the info!!! That was extremely informative. TDS is 3. I assume that is to much? And I'll turn the chamber vertically.
3 is a little high for RO/DI, by the time it gets that high you are releasing weakly ionized contaminants too and they don't measure well on a TDS meter. What is your tap water TDS and your RO only TDS before the DI? Those are the numbers used to figure your membrane efficiency or rejection rate. Since the membrane is the workhorse of the system and does 90-98% of the treatment it is important to know how it is working, otherwise you could be throwing DI resin at a poorly performing membrane and costing yourself money. Monitor all three TDS points frequently.
