The Planted Tank Forum banner
1 - 1 of 1 Posts

6 Posts
Discussion Starter · #1 ·
I have done a lot of research trying to verify various beliefs of the hobby over the years. I do them all the time. I am not sure if this sort of thing interests people here or if it is more of the faith based don't question the established dogma kind of places :)

Thought I would test the waters by posting some of my Chlorine investigations here. I am going to try to keep the wording super simple. I can be pretty wordy :)

I have heard many rumors about chlorine over the years. Things like you can dechlorinate just by leaving a bucket of water out over night or that you can "Age Water" instantly by adding Prime etc. Chlorine is very toxic to aquatic livestock so I wanted to know what the truth was.

I used 2 tests. A Hanna Model 711 Chlorine Checker. Also Insta-Test ANALYTIC Free & Total Chlorine test strips from LaMotte.

I wanted to see what amount of Chlorine was present in my water on that day.
Hanna Checker Reports 0.40 ppm at 75F and 0.80 at 50F IF no aerator is used on the faucet. With an Aerator (Normal) on the faucet I got 0.25 ppm Total Chlorine at 75F.
Next I wanted to see if the test strips were any good. I know test strips are usually inaccurate but by how much?

Further more I cannot tell you how many times I have got into arguments with LFS insisting that "We have Chloramine in this area". The truth is, I know we did not and will prove it 2 different ways in this article.

So to the test. The strips tell you how much free and also total chlorine you have. Chloramine only shows up in a total chlorine test and not a free chlorine test. So based on your results, that is how you tell the difference with the strips.

I would also like to mention that most info I can find says that Chlorine as low as 0.25 ppm could kill everything in your tank. I am sure it varies by species but I do not want any.

Here are the samples I took and the results:Sample 1
~75 F Tap Water
Chlorine smell and taste is evident.
Hanna Chlorine Checker reads 0.41 ppm
Test Strips Result 0 ppm for both Free and Total Chlorine.

Sample 2
~50 F Tap Water
Chlorine smell and taste is evident.
Hanna Chlorine Checker reads 0.80 ppm
Test Strips Result .5 ppm for both Free and Total Chlorine.

Sample 3
~110 F Tap Water
Chlorine smell and taste is evident.
Hanna Chlorine Checker not conducted
Test Strips Result 0 ppm for both Free and Total Chlorine.

I was alarmed to discover I can have Chlorine at 2x the toxic level and at aquarium water temperature and still have the test strips say nothing is there. I was also able to prove that we did have chlorine and not chloramine after all.
So Moving on to the next experiment.
Some people remove chlorine with a Carbon Block Filter when making RODI Water.

I wanted to see how good a single bock was. Most people use 2 for redundancy. I tested a brand new BRS Chlorine and VOC -5 Micron filter.

The water going in was 50F and 0.80 ppm.
Coming out was 0.02 ppm Total Chlorine.
I can see why the second Carbon Block is a good idea. If 0.25 ppm kills everything what can 0.02 ppm still do?

I decided to test an old rumor that has been hanging around the hobby that if you just leave the water in a bucket overnight the chlorine will off gas all by itself.
I left 5 gallons of water at 0.25 ppm total chlorine in a bucket for 7 hours.
Results: 0.21 ppm Total Chlorine.

That is no where near acceptable.

Next I wanted to test the idea that unless you break the surface tension the water does not do any gas exchange.

I used a power head. I intentionally put it deep in the bucket so that there was no turbulence in the surface. Just moved the water around a lot for 2 hours without disturbing the surface.
Results: 0.24 ppm Total Chlorine. It was 0.25 ppm before and this meter could easily be of by 0.01 ppm.

Next I tried it with an air stone to see if just bubbling it would remove all the chlorine. I started with the 0.24 ppm water from the previous experiment.

I used an air Stone (1" size) and a Model 10 Whisper air pump. This definitely breaks the surface tension but not a lot.
After 15 minutes 0.14ppm Total Chlorine.
After 9 hours 0.12ppm Total Chlorine.

So it does work but not very well at all.

Now I wanted to test my personal favorite. Prime by Seachem.

I started with 75F 0.25 ppm Aerated Chlorinated tap water.

After 10 minutes 0.00ppm Total Chlorine.

The Chlorine was probably gone much faster but it took my that long to get everything set up and the test ready and run.
I wanted to see what happened if I used prime with no aeration except for pouring the water into the bucket from a pitcher.

Added Prime to the bottom of the empty 5 gallon bucket. Poured in 5 gallons of aerated water of 0.25ppm chlorine into it from a 2 feet distance to get some disturbance in the surface. After that I just left it sit there for 25 minutes. Results were still 0.03ppm Chlorine. Much better but still of concern. I don't like it.


I wanted to re run the air stone test for a 24 hour period and also track pH which should rise as the CO2 goes out of the water. Here are the results. I found out my Checker is a little less accurate then I thought as you will see but still pretty good. I used a Hanna Phep 5 for Tempo and pH reading.

Temp 68.7 F
pH 8.07
Total Chlorine 0.40 pp, (This number is slightly lower then the results that come later so this is clearly not a precise instrument.)

After 20 minutes of aeration with an air stone:
Temp 68.5 F
pH 8.12 (CO2 is off gassing)
Total Chlorine 0.46 ppm (Again higher then the original so the test is not super accurate but it does show chlorine is not going down. An chlorine odor is still detectable too.)

After 1 hour of aeration with an air stone:
Temp 68.3 F
pH 8.21
Total Chlorine 0.42 ppm (Perhaps slightly less. Hard to say with this tests precision problems.)

After 10 hour of aeration with an air stone:
Temp 66.4 F
pH 8.46
Total Chlorine 0.18 ppm (Still a chlorine smell at the surface of the water and pH seems more stable when reading meter now)

After 27 hour of aeration with an air stone:
Temp 66.7 F
pH 8.50
Total Chlorine 0.16 ppm
No more chlorine smell that I can tell. If 0.25 ppm can kill all my fish then this number is still way to high.

I wanted to test IF the power head was pointed at the water surface could it off gas any better then an air stone.

Lastly I wanted to test the ability of power heads pointed at the surface to off gas the chlorine. I wanted to run this before but I ran out of test chemicals.

Used 50F water which tests 0.80 ppm Chlorine before I started the power head. I pointed it at the surface and made sure it was making a small wave and crashing against the other side of the 5 gal pale it is in.

After 14 hours water is 73F and chlorine is 0.29 ppm. 0.25 ppm is supposed to kill everything.

Last I really wanted to answer some questions about Chloramine I have heard over the years. Because we don't have any, I could not explore them. I wanted to answer such questions as:

If a hobbyist accidentally forgot to add Dechlorinator while doing a water change on a tank that was cycling, Could Chloramine really form?

Is the Ammonia Detectable before or after the Chloramine molecule is broken? Many say no but I call BS.

Here is what happened:

I used 50 F water from my tap. The Chlorine strips will not react with 75 F water and at 50 F they only seem to show about half of what is really there based on what my Hanna Total Chlorine Checker tells me.

In the past I have used around 1 drop of household ammonia for 1 gal of actual water and got a concentration of around 0.25 ppm from API.

In this case I did half a drop (By dilution with RODI) into 3 cups of water. According to my calculations this gives around 0.66 ppm of Ammonia which is definitely an appropriate level for a cycling tank. I got this number from a Hanna Ammonia LR Checker.

First I tested the cold water from the tap and got 0.5 ppm of both Free and Total Chlorine on the strips. This would really be more like 1 ppm if I had used the Hanna Total Chlorine Checker. The results mean that I have Chlorine and not Chloramine.

Next I added my 1/2 drop of Ammonia and stirred for a few seconds then retested. The test strips only take a few seconds to react BTW. The results were exactly what is "Supposed to happen". The Total Chlorine was still 0.5 ppm but now Free Chlorine is 0 ppm. This means the chlorine is now converted to chloramine.

Next I wanted to see how fast Prime could clear the water. I added 3 drops of prime and stirred for a few seconds and retested. Both Free and Total Chlorine now read 0 ppm. Impressive but be warned, these strips only show about half of what is there so it could be there were still dangerous levels. However, having previously investigated with my Hanna Checker I bet it really is close to 0.06 ppm or less of chlorine at this point. With light aeration it would be 0.00 ppm in a few minutes.

As an afterthought I wanted to see if the Ammonia was still detectable with an API during and after the prime did it's thing.

I repeated the set up. I verified that once I added the Ammonia I had Chlormanine. This time the strip said more like 0.35 ppm Total Chlorine and 0 ppm Free Chlorine. This would be around 0.7 ppm of Total Chlorine if I was using the Hanna Checker. I am saving those test chems for some upcoming tests I want to do :D Anyways I tests for ammonia with API and I got 0.75 ppm. I think so anyways because this color green is not even on the chart.

I added 2 drops of Prime and stirred and Retested. Both Free and Total Chlorine are now 0 ppm. I retested with API ammonia test. I was shocked to discover it only read 0.25 ppm. That is not what is supposed to happen as API is a Total Ammonia and not a Free Ammonia test as per the box. So the Ammonia is still detectable but at half of the amount. It is possible the prime might be changing how the test reads. Just wanted to share my findings.

The moral of this story is always use a dechlroinator and test for ammonia :D

That's all. I hope you enjoyed this info and that it may have answered some questions and makes you feel safer when dechlorinating.

I have many more experiments documented. I have spent a lot of time of aquarium chemistry and Algae. I have kept both Planted and Reef Tanks etc. If this is well received I can post more.
1 - 1 of 1 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.