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steve1981
07/19/2017, 08:41 AM
Hi everyone. I have two 125ltr water butts in my garage with a 4 stage RO machine hooked up. One is for salt and one for plain RO>

I uses Red Sea Coral Pro Salt and have always struggled with higher than usual nitrates.

I have just tested the fresh saltwater water (should be low TDS as just renewed all the gubbins) and the nitrates are showing as 5!!!

Any suggestions how or where this could be coming from?

Thanks, Steve.

LobsterOfJustice
07/19/2017, 08:47 AM
First step is to test the RODI water to see if the nitrate is coming from the water or the salt.


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devastator007
07/19/2017, 08:47 AM
"Should be low TDS", does this mean you haven't checked the TDS? If there's not TDS not Nitrate showing up in your DI water, than it must be coming from your salt mix.

steve1981
07/19/2017, 09:31 AM
"Should be low TDS", does this mean you haven't checked the TDS? If there's not TDS not Nitrate showing up in your DI water, than it must be coming from your salt mix.

I haven't checked it for 3 weeks as I can't find my tester. Going to get an inline one tomorrow. It was 0 3 weeks ago though.

steve1981
07/19/2017, 09:31 AM
First step is to test the RODI water to see if the nitrate is coming from the water or the salt.


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I'm using Red Sea marine care test kits, will it work in unsalted water though?

mcgyvr
07/19/2017, 10:36 AM
yep you need to test freshly made RO/DI water for TDS and nitrates..

Also RO/DI water is like a sponge and if left uncovered even for a little while will collect dust/dirt,etc...

bertoni
07/19/2017, 06:02 PM
The nitrate kit likely will work in fresh water, but you might want to ask the company. The Salifert kits will work in fresh or saltwater, if my memory is correct. I agree with testing the TDS of the fresh RO/DI water, at least.

steve1981
07/20/2017, 03:20 PM
Haven't had a chance to test the water for nitrates yet but TDS is showing 10!!! it was brand new filters a few weeks ago! Is 10 acceptable?

bertoni
07/20/2017, 03:33 PM
10 ppm is bad if the water for the sample was fresh from a RO/DI unit. The TDS can rise quite a bit in a container, as carbon dioxide and other things make it into the water, as has been stated. Does this setup have DI?

steve1981
07/21/2017, 01:53 AM
It wasn't direct from the RO no, it was tested from the container. I will test it directly from the RO unit when I get home. Yes it is 4 stage with two white filters (unsure what they are) the big carbon one and a DI resin canister. The carbon and resin was change a few weeks ago. I have more new resin to put in if need be.


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mcgyvr
07/21/2017, 08:08 AM
Are you sure its got a DI stage and not just a regular RO system?

But yes you need to test the direct output in a very clean glass container immediately after it comes out..

Stored water if opened even a little bit will collect dirt/dust,etc... and read higher TDS levels..

ReeferNoob4ever
07/21/2017, 03:12 PM
Is your container dirty?

steve1981
07/21/2017, 03:55 PM
Is your container dirty?



No it's brand new and has a lid


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steve1981
07/22/2017, 02:44 AM
Are you sure its got a DI stage and not just a regular RO system?

But yes you need to test the direct output in a very clean glass container immediately after it comes out..

Stored water if opened even a little bit will collect dirt/dust,etc... and read higher TDS levels..



I did a quick test last night and the water straight out of the RO was reading 119 TDS and 40 nitrates!!! However the water in the container (about 2 weeks old) was 11 TDS and 5 nitrates.

I am taking a wild stab that the water that I tested straight from the RO was off because it hasn't been on for a couple of weeks so the water sitting in it and in the pipes have been contaminated whilst it just sat there. I'll have to flush it through and test it again.


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steve1981
07/22/2017, 02:49 AM
https://uploads.tapatalk-cdn.com/20170722/133f9862e20b2892ee6ab3a0588ecfe9.jpg

Yes defo has DI. This is the one I have.


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bertoni
07/22/2017, 05:22 PM
What is the TDS of the tap water? Are you sure that the filter is plumbed correctly? 119 ppm out of RO sounds like you're testing the waste water or the RO membrane has failed.

steve1981
07/24/2017, 10:25 AM
What is the TDS of the tap water? Are you sure that the filter is plumbed correctly? 119 ppm out of RO sounds like you're testing the waste water or the RO membrane has failed.



Ok so I have done a few more tests.

From the tap... 275ppm
Direct from RO machine after letting run for a bit to flush through water that's been sitting in the filters for a few weeks... 10ppm with Nitrate reading 2. [emoji849]

How does that look like compared to everyone else's?


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bertoni
07/24/2017, 05:37 PM
Okay, 10 ppm seems reasonable for RO only. It should be zero after the DI phase, or the DI cartridge is shot or has some problem. Nitrate reading 2 ppm after RO is a bit discouraging, but it should be fine. What does the tap water read for nitrate?

outssider
07/24/2017, 06:00 PM
running the di canister horizontally will cause the water to channel. di needs to run vertical. If you want to run di horizontal you will need to re-pack (add a little more resin) often to keep water from channeling.

steve1981
07/24/2017, 10:37 PM
running the di canister horizontally will cause the water to channel. di needs to run vertical. If you want to run di horizontal you will need to re-pack (add a little more resin) often to keep water from channeling.



This is a good point and I noticed that earlier so I put a little more resin in but not happy with it so I will run it vertical on my days off.

I haven't tested directly from the tap but will do. I'll also refill the DI stage with brand new resin that I have.



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steve1981
08/03/2017, 12:31 PM
I've tested today and spoke with the manufacturer of the RO unit. He told me that although the unit should remove most nitrates, its not the design to do it specifically. He said if there is high nitrates to start, it won't remove all of them. Pretty much answered my question I think.

Thanks all.


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