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#1
12/20/2007, 12:31 AM
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frustrated with RO system
I have an RO system that keeps allowing Nitrates through after a few weeks with new filters. The TDS stays low (5-6) without DI, but the nitrate creeps up to about 5ppm. This is with new sediment filter, and carbon filter and RO membrane. How can there be nitrate in good RO water with low TDS. I do not run DI on this system because I make up to 750 gallons/ week with it and the DI would be really expensive at that rate. any ideas?
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#3
12/20/2007, 01:09 AM
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WOW. that was a tremendously helpful response. Thanks for closing the door on that one.
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#5
12/20/2007, 02:47 AM
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I only said to use the DI because I have the same problem where I live. The tap water TDS often exceeds 1500 here. My post RO TDS is between 12-20. I have measured 2ppm nitrate after the RO just recently. I found that using the DI is the only way for me to get quality water.
I did not answer the original post the way I did to be sarcastic, although I can see how it could have been (and was) interpreted that way without some more information on my part. I'm sorry. Maybe some more knowledgeable reefers can offer better help.
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My post disclaimer > IME only |
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#6
12/20/2007, 05:53 AM
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IIRC nitrate is one problem that ro membranes have troubles removing. As you already see. Perhaps look into water distillers, a little more money. But maybee not considering you make and waste so much water.
why do you make so much water anyways? 
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Its a good idea to have a refrence sample for alk test kits. 1.1350 grams of baking soda in 1gallon of distilled water=10dkh. Check your alkalinity test kit! |
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#7
12/20/2007, 09:14 AM
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What is the incoming nitrate level? Good 75 GPD RO membranes are about 90% effective on removing nitrates, 100 GPD Dows are a little less, probably in the 80-85% range.
The next question is what are you using to test the nitrates and do you trust it? And finaly as 30 said, use the DI. RO or DI by themselves, either one, are not completely effective on everything, especially nitrates, phosphates and silicates. It takes the whole enchilada to get good product water. |
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#9
12/20/2007, 10:04 AM
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my incoming tds is around 300. Nitrate is around5-10. I have heard that Nitrate is difficult to remove with RO because it is organic. Supposedly has something to do with chloramine as well. Whats weird is that the Nitrate starts off very low and builds up over a few weeks as the filters age. I am using salifert tests to test the levels.
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#10
12/20/2007, 10:06 AM
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You might try asking this over on the Spectrapure Sposnors forum. Maybe Charles, the owner has some ideas.
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#11
12/22/2007, 04:15 PM
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If your RO water has a tds of 5, running DI shouldn't be too aweful expensive. Your resin will last quite some time. With refillable cartridges and bulk resin available - I think DI is a reasonable way to go.
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RO/DI equipment and supplies at www.BuckeyeFieldSupply.com Sales@BuckeyeFieldSupply.com |
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