Chlorine won’t go away

[Midcoast]

Tl;dr - persistent chlorine levels in water for almost a week despite a 50% water change and a lot of dechlorinator. Is my next step another water change?

Last Sunday, about a week into cycling my first saltwater tank (29 Gal) , I noticed a very faint reading on my test strip for chlorine. Thought it was curious so I checked again the next morning and it had spiked up to about 5ppm. throughout Monday I added about 130 ml of tetra Aqua Safe (all I could get nearby on short notice) which brought the chlorine levels down to about 2-3ppm. Tuesday I did a 50% water change which brought it down to about .5 ppm, but still not 0. It has been at this level since Wednesday morning. I have since added a full 50ml bottle of prime over tues/wed with no change.

Anyone have any thoughts on what might be going on here? Chlorimides? But wouldn’t the levels of dechlorinator have taken care of that? Or is that my problem?

Is another 50% water change my next step?

 

[Fish Fan]

I'm sorry you're having some troubles with Chlorine. A couple of questions that I think may help Randy and others better help you would be are you doing all your testing using test strips, and are you using tap water?

Good luck!

 

[Midcoast]

I'm sorry you're having some troubles with Chlorine. A few questions that I think may help Randy and others better help you would be are you doing all your testing using test strips, and are you using tap water?

Good luck!

Yes, I have used the same brand of strip, that’s all I have at the moment for a chlorine test. It has read the same across 3 different containers of strips.

I have not used tap water. Filled the tank with saltwater for my lfs. All of my topoffs have been with distilled water and the 50% water change was done with water from my RO system at home. I tested this water before I added it and the chlorine was 0 .
For water movement I am using 2 power heads and an HOB filter with ceramic media. I also removed this media and rinsed with RO water and tested before re-adding.

 

[mfinn]

If you didn't add tap water and have not used any kind of chlorine, then it has to be faulty test strips.
Don't see how it can be any thing else.
False reading from the chemicals.

 

[mfinn]

@Randy Holmes-Farley

 

[Randy Holmes-Farley Verified Community Expert]

Nothing you are doing can cause a spike of chlorine from very little to 5 ppm.

I'd stop testing chlorine at all. I would not rely on the strips. The dechlorinators will easily get rid of it. Even if one bottle was not what it claims to be (say, someone bought it, used it, and returned it filled with water), two different bottles of different brands won't have that happen.

 

[Midcoast]

Nothing you are doing can cause a spike of chlorine from very little to 5 ppm.

I'd stop testing chlorine at all. I would not rely on the strips. The dechlorinators will easily get rid of it. Even if one bottle was not what it claims to be (say, someone bought it, used it, and returned it filled with water), two different bottles of different brands won't have that happen.

Appreciate your expertise, so just go back to adding ammonia/bacteria while I wait for a liquid ammonia test? I’m probably pretty much starting over at this point (presuming the highest rating I saw was to some extent chlorine/chloramine that would have killed the bacteria, correct?) ammonia is testing 0 with the liquid API saltwater master kit.

 

[Randy Holmes-Farley Verified Community Expert]

Appreciate your expertise, so just go back to adding ammonia/bacteria while I wait for a liquid ammonia test? I’m probably pretty much starting over at this point (presuming the highest rating I saw was to some extent chlorine/chloramine that would have killed the bacteria, correct?) ammonia is testing 0 with the liquid API saltwater master kit.

Have you added any bacteria or ammonia yet?

I would not add more of either until you get an ammonia test.

 

[Midcoast]

Appreciate your expertise, so just go back to adding ammonia/bacteria while I wait for a liquid ammonia test? I’m probably pretty much starting over at this point (presuming the highest rating I saw was to some extent chlorine/chloramine that would have killed the bacteria, correct?) ammonia is testing 0 with the liquid API saltwater master kit.

Have you added any bacteria or ammonia yet?

I would not add more of either until you get an ammonia test.

I added some a couple days ago but the “reading” on the strip never changed fwiw. I have not added any since.

 

[Fish Fan]

I'm just going to add that those test strips are not typically a reliable way to test aquarium water, and I think they may be a large part of your difficulties. They are mostly made for testing swimming pools, even if there happens to be a picture of a fish on the package of strips that you have. And, as a pool owner I can say that they are not even well liked for testing swimming pools

The API test kits can be found inexpensively at any PetCo or most pet shops, and while the API brand doesn't get a lot of love here on R2R, they are fine for things like cycling your tank, in my experience; much better than strips, I believe. For not much more money at all, check out the test kits by Salifert, these are inexpensive and most reefers agree that they are typically reliable. The only down side is that not a lot of local stores will have them, you may have to order the Salifert kits.

 

[jollyg97]

I am simply speculating but I remember years ago I was terrified of ammonia in my first reef tank. I was too early with a clownfish and my ammonia went up to .5 ppm. I then dosed ammonia lock to counteract the ammonia. Retested immediately and found that my api ammonia test jumped off the charts! As dark of a greenish blue as it could possibly get.

Turns out that the ammonia lock was for some reason causing a reaction with the test and causing false heavy positive on my tank. I do not understand why they reacted like this but it 100% happened to me.

The speculation part for me is if it’s possible that the dechlorinating agent is interacting with your tests, and giving a false positive? I’m not an expert with testing agents and I just wanted to share my strange experience from the past. Also I believe that chlorine evaporates at a pretty brisk pace so not much of this makes sense in terms of actually having chlorine going UP over time.

Regardless always use 0 TDS RODI or worst case scenario distilled. I do not trust LFS stores with their RODI unless they show me 0 TDS. Had an issue in the past with that as well.

I would leave things alone, not rush different methods and see where things are after a little bit of time. Less can certainly be more with saltwater tanks, unless you’re extremely certain of what you’re doing you can do more harm than good throwing darts at an issue. I learned that the hard way when I was first getting into the hobby.

 

[Midcoast]

Just got back from the LFS, they didn’t have any liquid tests for sale, but they tested a sample I took in and it came back 0. It could well be an interaction of *something* in the water. I’ve ordered a liquid test from Amazon to use for future tests