RO water testing

[gmcc14]

Hi everyone,

I recently realized that the API nitrate test that I was using was giving me false low nitrate readings when I took a water sample to my LFS and their Salifert test read very high nitrates. Since then I bought my own Red Sea and Salifert test kits and my nitrates are over 60. I started dosing Red Sea nopox but would like to get the bottom of the cause of my nitrates. I bought a TDS meter and tested the RO from my LFS and it read 131ppm! I assumed their RO unit was faulty and went to another LFS to get RO. I told them about the 131 reading from the other LFS and they were convinced that was the cause of my high nitrates. They filled me up and when I got home and tested their water with the TDS it read 171! I bought another TDS meter (different brand) and got similar results. Could this be from my containers? I am using old salt containers that I rinse with tap water. (My tap TDS reading is 65ppm.) Should I be cleaning the containers with a water/vinegar mix before refilling? I read some people clean their home RO unit barrels with a water bleach mix, is this the way to go? Could this be the cause of the high nitrates in my tank. All fish and corals doing very well. Mostly soft and LPs but all growing well thank goodness. Any advice would be greatly appreciated!

 

[ebushrow]

Those are both crazy high readings....is the water you buy just plain rodi? Or saltwater mix?....I think I can say with confidence, that we all use old salt buckets to either transport water or mix water, so it’s not the “bucket” itself. It never hurts to do a water/vinegar bath, but it is doubtful that that is the cause of your nitrates.....I would say it’s the rodi you are getting. Ask the LFS to show you the TDS readings from their rodi units and see what they say....it may be that the tds meters you purchased need to be calibrated first, and like most instructions are hard to follow or so small they give you a headache. Just my 2cents here though.

 

[sbash]

Okay, let's start with the obvious, have you considered getting your own RO/DI unit?

If you cannot do that, you might as well get distilled water from your local grocery store (half joking, but it might be better)...

Okay, so onto your real question...

Are you testing the water straight out of the LFS container, or after it goes into your container?

Generally speaking, you should not need to clean your freshwater reservoirs (containers) between uses. However, if the water you are putting into it has contaminates, then it could benefit from a rinse.

Sounds like there is something wrong with your local supply of "RO" water. I doubt my well water tests above 150 TDS, and there is some funky stuff in that... Anyway, if I bought RO/DI water that was more than 0tds, I would have a serious chat with the supplier...

 

[gmcc14]

Those are both crazy high readings....is the water you buy just plain rodi? Or saltwater mix?....I think I can say with confidence, that we all use old salt buckets to either transport water or mix water, so it’s not the “bucket” itself. It never hurts to do a water/vinegar bath, but it is doubtful that that is the cause of your nitrates.....I would say it’s the rodi you are getting. Ask the LFS to show you the TDS readings from their rodi units and see what they say....it may be that the tds meters you purchased need to be calibrated first, and like most instructions are hard to follow or so small they give you a headache. Just my 2cents here though.

The water I'm buying is straight RODI, I will try a third LFS tomorrow.

 

[gmcc14]

Okay, let's start with the obvious, have you considered getting your own RO/DI unit?

If you cannot do that, you might as well get distilled water from your local grocery store (half joking, but it might be better)...

Okay, so onto your real question...

Are you testing the water straight out of the LFS container, or after it goes into your container?

Generally speaking, you should not need to clean your freshwater reservoirs (containers) between uses. However, if the water you are putting into it has contaminates, then it could benefit from a rinse.

Sounds like there is something wrong with your local supply of "RO" water. I doubt my well water tests above 150 TDS, and here is some funky stuff in that... Anyway, if I bought RO/DI water that was more than 0tds, I would have a serious chat with the supplier...

I'm testing the water after I get it home ( been in container for 30 mins or so). Sounds like I have to ask my LFS to test the water before filling.

 

[Randy Holmes-Farley Verified Community Expert]

While the quality of the source water is worth checking out carefully (especially for other reasons, such as copper), nitrate comes from food metabolism. If the tank has elevated nitrate, that is nearly always the primary source if you are not using straight tap water.

 

[Randy Holmes-Farley Verified Community Expert]

This has more on where nitrate comes from and how to reduce it:

Nitrate in the Reef Aquarium - REEFEDITION
https://www.reef2reef.com/blog/nitrate-in-the-reef-aquarium

 

[gmcc14]

This has more on where nitrate comes from and how to reduce it:

Nitrate in the Reef Aquarium - REEFEDITION
https://www.reef2reef.com/blog/nitrate-in-the-reef-aquarium

Thanks, this is really helpful!

 

[gmcc14]

Those are both crazy high readings....is the water you buy just plain rodi? Or saltwater mix?....I think I can say with confidence, that we all use old salt buckets to either transport water or mix water, so it’s not the “bucket” itself. It never hurts to do a water/vinegar bath, but it is doubtful that that is the cause of your nitrates.....I would say it’s the rodi you are getting. Ask the LFS to show you the TDS readings from their rodi units and see what they say....it may be that the tds meters you purchased need to be calibrated first, and like most instructions are hard to follow or so small they give you a headache. Just my 2cents here though.

So I went to another LFS and got two containers of RO from them, both read 3ppm on both of my TDS meters. I guess both of the other stores need to change the filters on their RO units.

 

[Randy Holmes-Farley Verified Community Expert]

Thanks, this is really helpful!

You're welcome.

Happy Reefing.

 

[Ty Hamatake]

So I went to another LFS and got two containers of RO from them, both read 3ppm on both of my TDS meters. I guess both of the other stores need to change the filters on their RO units.

This is crazy! I would consider letting the other two stores know about your results. They may tell you that it's user error, but at least you can check off your good deed for the day

What is your stocking, feeding, and water change schedule? Nothing is more efficient at bringing nitrates down than water changes, and I'd say smart feeding/stocking is the easiest (and cheapest) way to keep them down.

 

[Randy Holmes-Farley Verified Community Expert]

Nothing is more efficient at bringing nitrates down than water changes, and I'd say smart feeding/stocking is the easiest (and cheapest) way to keep them down.

How are you defining "efficient" in that claim?

 

[Randy Holmes-Farley Verified Community Expert]

So I went to another LFS and got two containers of RO from them, both read 3ppm on both of my TDS meters. I guess both of the other stores need to change the filters on their RO units.

Are the claiming it is RO water, or RO/DI water?

 

[Ty Hamatake]

How are you defining "efficient" in that claim?

Cost and time.

I know it had to be paid for at some point, but unless you are a zero water change kind of reefer, most people will have salt and water on hand. No extra equipment costs for a reactor and media or other types of chemical or biological filtration. Even if you don't keep up with frequent water changes, IO is around 60 bucks a box that's good for 200 gallons. So in theory you could reduce nitrates by half in a 400 gallon system... right? (This is kind of the base of the "time efficiency" as well, so if that's incorrect so is this next piece )

Time wise (again in theory) you can almost instantly reduce nitrates by whatever percentage of water you change, assuming your new water is at 0 ppm.

I know this would be an extremely temporary fix, but in my original post this was to only get NO3 down. Keeping it down is another story.

If this is incorrect, bad info, or flawed in any way please let me know! I really don't like being wrong, but if I have to be wrong about something to someone, I chose reef chemistry to @Randy Holmes-Farley