ICP Test with Chlorine

[Nathaniellund17]

Hello All,
I have a 2 and a half year old reef tank with 230 gallons. It's a mix between LPS and SPS - though to date I have not had much success with some SPS. All of my parameters are in check for the "standard' checks:
Salinity = 1.026
PH = 8.2 (apex monitor)
Nitrate = 12 (hanna checker)
Phosphate = .05 (hanna checker)
Alkalinity = 8.5 (hanna checker)
Calcium = 440 (salifert test)

I finally sent some samples in for an ICP test as I couldn't for the life of me figure out what was going on with my SPS corals.

I sent a sample of my display tank, and a sample from my RODI water.

The display tank shows Chloride as 22,659 ppm.

My RODI water shows Chloride as 650 ppm.

My LFS thought the main problem was the RODI water, which would make sense as if you remove the 650 ppm from the display, that brings it to 22K, which is still really high, but it's within ICP's range. Right now, I'm currently using a 7 stage RO unit from BRS with 2 carbon blocks. In talking with the LFS and BRS, they both recommended I use ChloraGuard carbon block in place of one of the standard blocks.

The questions I have is what Chloride test can you use to test the Chloride in the water - so you know when to switch out the carbon blocks? I went to Home Depot and got a Chloride test kit for swimming pools, which tests water up to 5 ppm. I would think this test would really show chloride as my RO water has 650 ppm. When I tested the water (from the same RO water that I pulled my ICP test sample from) I'm getting no coloration... meaning 0 chloride. Could it be that the test doesn't test for all "types" of chloride - as in maybe I need to get a chloramine test?

 

[Auto-pilot]

So have you used a tds reader on your water from the filters. Honestly my opinion would be that there is something wrong with your filter to let that much though. There's no way it's working letting 650 ppms through it. I would use a tds reader to test the water going in and coming out. Tds pens are super cheap and a good way to ensure your filters are working. You should have 0ppm coming out of that filter, if you don't there is something wrong with it. The chlorine is high because it's building up in your tank from dirty water.

 

[Nathaniellund17]

Does TDS measure Chlorine? To answer your question, yes I have a TDS meter, and it has consistently read zero at the last stage of the output.

 

[Auto-pilot]

I just looked it up and it does not, I thought it would. Yeah if it reads zero it's doing its job. Not sure if there is a specific filter you can add that targets chloride.

 

[Nathaniellund17]

My understanding is that it’s usually the carbon blocks that remove most of the chlorine. I believe that’s why it was recommended to use the chloraguard carbon block. I just began running the rodi unit again with brand new filters - with one being the chloraguard. I ran the swimming pool chlorine test, and it shows zero chlorine. I then ran an API ammonia test, and I’m getting about 1.0 ppm reading… which I’m thinking tells me there is definitely some chlorine in the water. Is that a way to determine if I have chlorine? I’m at a loss right now.

My livestock seem to be fine… I have 4 tangs, 2 clown, 3 wrasse, 1 blenny, 3 gobies, 1 anemone, 1 clam, multiple shrimp and snails… none of which look stressed. Whatever is going on I think has been like this since I began the tank. Based on these readings, I would think I’d have a lot more problems than what I’m having.

 

[Randy Holmes-Farley]

So let's back up.

Chlorine by ICP in a reef tank means chloride, which is the most abundant ion in natural seawater at more than 19,000 ppm. Assuming the chlorine values are accurate, its primary utility is judging salinity.

The chloride in the RO/DI is simply inaccurate . Ignore it. Which company? Not all ICP companies are reliable.

Chloride is not ever removed by carbon block. it is entirely removed by a DI.

 

[Nathaniellund17]

Thanks for the comments. So my understanding is that carbon blocks will remove standard chlorine, but have a hard time with chloromines, which is why there are special carbon blocks filters.

Here’s what it says from the BRS website:

If you prefer to check yourself, you can test the waste water coming from your RO/DI system with a total chlorine test kit. Because standard carbon block filters remove all traces of chlorine, if your waste water still tests positive for total chlorine, it would mean that your tap water most likely contains chloramine.

The ICP company I used was ICPAnalysis.

i agree it’s weird that I’m getting a zero chlorine reading from the pool test kit, which agree that the test could be a false positive. But what are thoughts on the ammonia in the RODI water?

 

[Randy Holmes-Farley]

What is weird about getting zero? IMO, that is normal.

In my testing for my chloramine article, normal carbon blocks are pretty decent and I did not need anything special. IMO, a lot of that is overhype by resellers of more expensive devices.

If the DI is depleted, or close to it, there will be ammonia in the RO/DI water if your water company uses chlormamine (which is also easy to look up). It can actually be much higher in the effluent than the incoming water if the DI has collected a lot of ammonia (as it will if you have chloramine), and then release it when the DI begins to deplete and more strongly bound ions such as sodium or calcium displace it.

Overall, the only think problematic that I see is the false chlorine reading by icp analysis, and as I said, not all ICP companies give reliable data.

 

[Randy Holmes-Farley]

These have more:

Chloramine and the Reef Aquarium - Reefkeeping.com

Reverse Osmosis/Deionization Systems to Purify Tap Water for Reef Aquaria by Randy Holmes-Farley - Reefkeeping.com

 

[Auto-pilot]

My understanding is that it’s usually the carbon blocks that remove most of the chlorine. I believe that’s why it was recommended to use the chloraguard carbon block. I just began running the rodi unit again with brand new filters - with one being the chloraguard. I ran the swimming pool chlorine test, and it shows zero chlorine. I then ran an API ammonia test, and I’m getting about 1.0 ppm reading… which I’m thinking tells me there is definitely some chlorine in the water. Is that a way to determine if I have chlorine? I’m at a loss right now.

My livestock seem to be fine… I have 4 tangs, 2 clown, 3 wrasse, 1 blenny, 3 gobies, 1 anemone, 1 clam, multiple shrimp and snails… none of which look stressed. Whatever is going on I think has been like this since I began the tank. Based on these readings, I would think I’d have a lot more problems than what I’m having.

I hate the API ammonia test, Imo it's hard to use and unreliable. Is there a chance the ammonia is just false positive?

 

[Nathaniellund17]

These are great articles, thank you!

So here’s what I’m thinking after reading them. The 650 ppm reading on the rodi water is most likely a false reading. From these articles, I’m thinking tap water doesn’t even come close to 650 ppm (everything I’m reading talks of <1-5 ppm as standard). So just seeing 650 ppm does not make sense. Does this sound right?

The carbon blocks are probably doing their job as when I test the output, I’m not seeing any chlorine. Do you think a pool tester is good enough to detect chlorine? One test I’m going to do is check my tap water to see if there’s chlorine there.

The ammonia is coming from the byproduct of removing other contaminants (most likely chloromine). The DI removed it initially, but could be collecting it over time and releasing it as other chemicals take their place. I’m pretty good about changing out my anion resin. The colors change fast on it see I can tell it’s getting depleted. However my cation never really changes color, so I don’t change it out nearly as often. I also have a mixed bed resin that I change slightly more frequently than the cation, but again, it doesn’t change color like the anion, so doesn’t appear that it’s getting depleted.

I’m going to do a few more tests, but if all this holds true, then I’m not sure my water is my problem.

 

[Nathaniellund17]

I hate the API ammonia test, Imo it's hard to use and unreliable. Is there a chance the ammonia is just false positive?

That’s definitely a possibility. Is there a better test you recommend?

 

[Auto-pilot]

Honestly I like the salifert one is a little better. There are just too many false positives with the API because the color comparison. The best is the Hannah egg test but I don't test amonia enough to justify spending 70$. I don't really test amonia anymore and haven't started a new tank In a while.

 

[Randy Holmes-Farley]

So here’s what I’m thinking after reading them. The 650 ppm reading on the rodi water is most likely a false reading. From these articles, I’m thinking tap water doesn’t even come close to 650 ppm (everything I’m reading talks of <1-5 ppm as standard). So just seeing 650 ppm does not make sense. Does this sound right?

It cannot be anything except a false reading. Regardless of the likelihood of raw tap water having 650 ppm chloride (very low), or all of it getting through an RO/DI (extremely low), the values are actually impossible since there are no positively charged ions present to offset the negative charge fro chloride. You would need similar amount of cations, such as sodium, potassium, calcium, or magnesium, and they are not present.

The carbon blocks are probably doing their job as when I test the output, I’m not seeing any chlorine. Do you think a pool tester is good enough to detect chlorine? One test I’m going to do is check my tap water to see if there’s chlorine there.

Any cheap chlorine test is usually adequate, but yes, check the tap water.

I agree that I do not see any substantial problem with your water.

 

[Nathaniellund17]

Honestly I like the salifert one is a little better. There are just too many false positives with the API because the color comparison. The best is the Hannah egg test but I don't test amonia enough to justify spending 70$. I don't really test amonia anymore and haven't started a new tank In a while.

I agree with the Hannah. I didn’t really start testing until this last week again as I thought I was good with a cycled tank. Really appreciate the feedback.

 

[Nathaniellund17]

It cannot be anything except a false reading. Regardless of the likelihood of raw tap water having 650 ppm chloride (very low), or all of it getting through an RO/DI (extremely low), the values are actually impossible since there are no positively charged ions present to offset the negative charge fro chloride. You would need similar amount of cations, such as sodium, potassium, calcium, or magnesium, and they are not present.



Any cheap chlorine test is usually adequate, but yes, check the tap water.

I agree that I do not see any substantial problem with your water.

Okay, I think I'm still not comfortable with what's happening. First, here are the tests I ran.

I ran the chlorine test on the following locations:
1. Tap water - 0 (clear water)
2. Reef tank sump water - 0 (clear water)

I would expect the test to have some chloride with the sump because of the saltwater. Am I correct in thinking this? This leads me to believe that there's something wrong with the test I'm using - or I'm testing it incorrectly. (it seems to be a simple test of filling up a vile to a level then adding 5 drops... so not sure how I could be performing it incorrectly).

Next tests I ran were the API ammonia test:
1. RODI water I ran yesterday with fresh carbon blocks, fresh anion and fresh mixed bed resin. Came back somewhere between .25 and .5 ppm.
2. RODI water I ran today with the difference being fresh cation resin. Came back somewhere between .25 and .5 ppm.
3. Reef tank sump water after running carbon and an ammonia pad overnight through the sump. Came back somewhere between .25 and .5 ppm.

With these tests, I'm thinking that being that because I'm getting the same results... maybe the test is bad and I should calibrate up. Or maybe I should just get a new ammonia test. Again none of my livestock seems stressed. Would welcome thoughts?

So the last question I have is I looked up my cities water quality report from this last year that was published March 15, 2023. It's showing that the chloride is between 134 - 420 ppm (collection date is from 2020, but it is the most recent report.) I thought tap water would have chloride between 0-5 ppm. How can this be so high? Maybe I'm misinterpreting this?

 

[Randy Holmes-Farley]

You are still confusing chloride and chlorine.
There is no problem here looking for an explanation.
The water report shown does not mention chlorine. It shows chloride and other ions. There may be another part of it discussing chlorine or chloramine or other ways of killing bacteria.

The icp test of the ro/di showing massive chloride is in error.

 

[Nathaniellund17]

You are still confusing chloride and chlorine.
There is no problem here looking for an explanation.
The water report shown does not mention chlorine. It shows chloride and other ions. There may be another part of it discussing chlorine or chloramine or other ways of killing bacteria.

The icp test of the ro/di showing massive chloride is in error.

Any thoughts with the ammonia tests, should that be a concern?

 

[Randy Holmes-Farley]

Any thoughts with the ammonia tests, should that be a concern?

API ammonia frequently gives false positives in the 0.25 to 0.5 ppm range.

 

[Nathaniellund17]

API ammonia frequently gives false positives in the 0.25 to 0.5 ppm range.

Thanks!