Bleach affected by seawater?

Reefahholic · Dec 11, 2018

When you clean and sterilize a QT tank...it's been said it's best to fill it up with cold water rather than hot water if you're using bleach. Hot water apparently decomposes the active ingredient of bleach and renders it ineffective.?

My question is...would bleach be changed at all if it's used in saltwater rather than freshwater?

We're trying to figure out the correct dose to use to sterilize 10 gallons of water. Then i'm wondering if the water would play a role in potency if it's saltwater or freshwater. It may not matter...I don't know.

My last question is...does bleach nuke everything, or do you guys think there is a possibility that some parasites, organisms, dinoflagettes, etc that would survive?

wesman42 · Dec 11, 2018

Would you mind sharing which research shows that using bleach at a higher temperature breaks it down? I feel like this is considerable misinformation.

Reefahholic · Dec 11, 2018

wesman42 said:
Would you mind sharing which research shows that using bleach at a higher temperature breaks it down? I feel like this is considerable misinformation.

Sure, it was from this website. Not sure how accurate this is. I do know when I've used bleach in hot water previously, it created a white residue inside the tanks. So it's having some kind of strange reaction.

https://www.info.gov.hk/info/sars/en/useofbleach.htm

Cold water should be used for dilution as hot water decomposes the active ingredient of bleach and renders it ineffective. Bleach containing 5.25% sodium hypochlorite should be diluted as follows (demonstration short):

Reefahholic · Dec 11, 2018

Then for the Clorox website:

https://www.clorox.com/how-to/laundry-basics/bleach-101/hot-water-and-bleach/

Q. I have a friend who told me that in college he was told that hot water makes bleach less effective. Is this true? I always wash my whites in the hottest water. Thank you for your input.

A. Thanks for the great question. Here is what I would tell your friend: washing white and safely bleachable colorfast items with Clorox® Regular Bleach2 in the hottest water possible will give you the best cleaning and whitening performance because its effectiveness increases with temperature. Perhaps you would like to avoid an “I’m right, and you’re wrong” gloating response to his opinion (not really good for a friendship) by applying what he was told to the proper storage of bleach. In that case, he is correct: Clorox® Regular Bleach2 should ideally be stored at room temperature (70°F) because the active ingredient in liquid bleach, sodium hypochlorite, is very sensitive to high heat storage conditions. Basically, you want to store it at normal room temperature to prolong its active life, and when you add it to a load of laundry, use hot water because you want it as active as possible for the best performance. As a bleach user, he definitely sounds like a friend worth having!

I'm confused...

ReeferReefer · Dec 11, 2018

I am pretty sure you can use hot water with bleach. I don't think salt water would make it less effective either.

Dan_P · Dec 11, 2018

The temperature concern is around storage of 5% bleach. Higher temperatures will speed up the decomposition of full strength bleach. When you use bleach, you dilute it and using it over a shorter time period, so, the decomposition reaction under these conditions does not play an important role. That is how you “get away” with hot water bleaching being better.

If you are sanitizing saltwater with bleach, there might be some loss to trace metals and organics. Best to test the bleach concentration to confirm it is at the level you want. I presume you will reduce the chlorine with thiosulfate or some other reducing agent.

Super Fly · Dec 11, 2018

Reefahholic said:
We're trying to figure out the correct dose to use to sterilize 10 gallons of water. Then i'm wondering if the water would play a role in potency if it's saltwater or freshwater. It may not matter...I don't know.

My last question is...does bleach nuke everything, or do you guys think there is a possibility that some parasites, organisms, dinoflagettes, etc that would survive?

This is the dosage amount I used to sanitize used tank;
Vinegar – 1 White Distilled Vinegar to 4/5 parts water to remove coraline and hard minerals (I used 4 gal vinegar for 90 gal tank)
Chlorine – 2 capfulls to 5 gal water for equipments to sanitize. (I used 1 cup of bleach for 90 gal.) Let run for 24 hrs, drain and add clean water and run with 2 bags of chemipure for 24 hrs. Drain tank and let it dry, bleach will evaporate.

Yes, bleach will nuke everything. I always used the above method on all used equipment and never had issue.