Using chlorine to disinfect a QT

[Humblefish]

I wanted to document this entire process, explain how to do it and what to expect to achieve from doing it. Reading this thread will provide some background info.

First off, you cannot expect to achieve complete sterilization from dosing chlorine into a QT. Eradicating Ich (Cryptocaryon) tomonts, for example, requires maintaining 60 mg/L chlorine for 24 hours (source here - Table 2); but that seems difficult to achieve. Also, I think using that much chlorine could damage equipment/pumps used in a QT.

So the concentration I am shooting for with this experiment is 10ppm (or mg/L). According to this source that should be good enough to reduce most bacteria, protozoa and virus populations by 99.99%. What I'm most concerned with is heterotrophic bacteria building up in a long-term QT. These bacteria use organic carbon as a food source and thus, will biodegrade most medications (excluding copper) if their populations are left unchecked. (My rationale for believing this can be found here.) So the goal is to knock them back periodically by hammering these bacteria with chlorine. Instead of having to break down & sterilize (via drying) a long-term QT from time to time.

With this in mind, I've setup a 10 gal QT with all the usual equipment (photo below - removed some water to avoid bleach splashing out of the tank). This morning @ 9am I dosed 1/4 cup of regular liquid bleach (8.25% sodium hypochlorite) to achieve 10ppm chlorine. (Actually, just slightly higher than 10ppm.) This turned the QT cloudy and slightly yellow. I will continue to test the chlorine level every 8 hrs to see how long it takes for it to fully evaporate. And then drop a damsel in for good measure. I will also examine all QT equipment in a week or two to ensure no damage has been done from the chlorine.



Monday @ 9am: >10ppm chlorine
Monday @ 3pm: >10ppm chlorine (+6 hrs)
Tuesday @ 12am: >10ppm chlorine (+15 hrs)
Tuesday @ 10am: >10ppm chlorine (+25 hrs)
Wednesday @ 10am: >10ppm chlorine (+49 hrs)
Thursday @ 1pm: >10ppm chlorine (+76 hrs)
Friday @ 1pm: >10ppm chlorine (+100 hrs)
Saturday @ 1pm: >10ppm chlorine (+124 hrs)
Monday @ 1pm: 10ppm chlorine (+172 hrs) (1 week, 4 hrs)
Wednesday @ 1pm: 8ppm chlorine (+220 hrs)
Friday @ 1pm: 3ppm chlorine (+268 hrs)
Saturday @ 3pm: 2ppm chlorine (+294 hrs)
Sunday @ 3pm: 0.5ppm chlorine (+318 hrs)
Monday @ 2pm: NO DETECTABLE CHLORINE (+341 hrs) (2 weeks, 5 hrs)

 

[twilliard]

I wanted to document this entire process, explain how to do it and what to expect to achieve from doing it. Reading this thread will provide some background info.

First off, you cannot expect to achieve complete sterilization from dosing chlorine into a QT. Eradicating Ich (Cryptocaryon) tomonts, for example, requires maintaining 60 mg/L chlorine for 24 hours (source here - Table 2); but that seems difficult to achieve. Also, I think using that much chlorine could damage equipment/pumps used in a QT.

So the concentration I am shooting for with this experiment is 10ppm (or mg/L). According to this source that should be good enough to reduce most bacteria, protozoa and virus populations by 99.99%. What I'm most concerned with is heterotrophic bacteria building up in a long-term QT. These bacteria use organic carbon as a food source and thus, will biodegrade most medications (excluding copper) if their populations are left unchecked. (My rationale for believing this can be found here.) So the goal is to knock them back periodically by hammering these bacteria with chlorine. Instead of having to break down & sterilize (via drying) a long-term QT from time to time.

With this in mind, I've setup a 10 gal QT with all the usual equipment (photo below - removed some water to avoid bleach splashing out of the tank). This morning @ 9am I dosed 1/4 cup of regular liquid bleach (8.25% sodium hypochlorite) to achieve 10ppm chlorine. (Actually, just slightly higher than 10ppm.) This turned the QT cloudy and slightly yellow. I will continue to test the chlorine level every 8 hrs to see how long it takes for it to fully evaporate. And then drop a damsel in for good measure. I will also examine all QT equipment in a week or two to ensure no damage has been done from the chlorine.



Monday @ 9am: >10ppm chlorine
Monday @ 3pm: >10ppm chlorine (+6 hrs)
Tuesday @ 12am: 10ppm chlorine (+15 hrs)

I am tagging along on this as it will also help me in my work with bleach
Thank you!

 

[Humblefish]

Think I might have overdosed it... 25 hrs later and its still sitting @ 10ppm. lol

Should have started out with 5ppm.

 

[Brew12]

My first thought was that a UV light would help the clorine break down much faster.

My second thought was that a UV light might sterilize the tank well enough for what you want it to do without the bleach.

A higher temp should help the clorine break down too.

 

[Tankr75]

Following.

 

[Pola0502ds]

Just in time humble! I was looking just for this!! Thank you!

 

[Humblefish]

So basically, I screwed up. I should have followed this dosage guide: http://dec.vermont.gov/sites/dec/files/dwgwp/DW/chlorinedosageemergencydisinfection.pdf

According to that chart, I should have only dosed 1.25 teaspoon of liquid bleach (8.25% sodium hypochlorite) to achieve 10ppm chlorine.

Instead I dosed 1/4 cup (or 12 teaspoons) so by my calculations I ran the chlorine level up to almost 100ppm. dang.

 

[Tankr75]

Have you tried raising the temperature to around 90 degrees. That will help evaporate the chlorine.

 

[Humblefish]

Have you tried raising the temperature to around 90 degrees. That will help evaporate the chlorine.

Yes. However, I will need to conduct another experiment dosing the appropriate amount to achieve only 10ppm. I guess the only useful thing about this run will be to see how well my equipment holds up vs. extreme chlorine. This concentration should have been high enough to kill even ich tomonts, which might be useful to someone in the future. So its not a total waste.

 

[Tankr75]

That is true. No experiment is a waisted one. We always learn something lol.

 

[Tankr75]

Might is ask what you're using to measure the chlorine

 

[Humblefish]

Might is ask what you're using to measure the chlorine

Just a cheap chlorine pool test kit: http://www.lesliespool.com/Leslies-...-Count-in-a-Waterproof-Bottle/LES-2977-12.htm

I should have ordered a better one online that tested higher concentrations. That one maxes out at 10ppm.

 

[Humblefish]

But it was doing a pretty decent job measuring the QT's pH & alkalinity until I nuked it with too much chlorine.

 

[Brew12]

That is true. No experiment is a waisted one. We always learn something lol.

So true, even if it is only how to measure!

 

[Tankr75]

Lol yea. Well if you don't mind I might run this test with you. I have a 10 gallon qt I was looking at trying to disinfect. I have a 30,000 gallon pool and we use liquid bleach instead of the tablets to keep it clean. And I have a bunch of test strips left over.

 

[Humblefish]

Lol yea. Well if you don't mind I might run this test with you. I have a 10 gallon qt I was looking at trying to disinfect. I have a 30,000 gallon pool and we use liquid bleach instead of the tablets to keep it clean. And I have a bunch of test strips left over.

Go for it! As far as I can tell, this should be a solid dosing guide: http://dec.vermont.gov/sites/dec/files/dwgwp/DW/chlorinedosageemergencydisinfection.pdf

Check the liquid bleach you are using, but it should say "8.25% sodium hypochlorite" under ingredients. If so, you'll need to dose 1 1/4 teaspoon based on my calculations to achieve 10ppm chlorine. But that's only if the 10 gallon is completely full.

 

[Tankr75]

Ok cool. Are you leaving all of your equipment in the tank? Airstone heater filter Ectra.

 

[Humblefish]

Ok cool. Are you leaving all of your equipment in the tank? Airstone heater filter Ectra.

Yes. A small powerhead, HOB powerfilter, heater, thermometer, even a PVC elbow. I only used cheap stuff because I want to inspect them all for damage/rust after the chlorine totally evaporates.

 

[Tankr75]

Ok cool. I will start my test tonight.

 

[rayn]

Interesting for sure. Following along