Watering and evaporating chlorine


I have an indoor grow going and was told before I water to let the water sit out for 24 hours in order for the chlorine to evaporate…is there a problem leaving it out longer than that? Basically can I always have water out and ready to go, or is it detrimental to leave it out too long?


I leave mine out 2-3 days with an airstone in my water buckets to help expedite the process.



If you want too leave it out extended periods of time then you actually need an airstone so your water doesn’t start to go stagnant from lack of oxygen and circulation.



What would you consider an extended period of time?


Just like any body of water, it should be able to go indefinitely as long as anaerobic bacteria doesn’t begin to breed in there.

Honestly, if you were to go to the nastiest pool of water you can find, collect a 5 gal bucket of it, put some bleach in it yourself, and begin to pump air into it, you would reach a point (I’m not sure when) that you could use that water to grow


If it is being pumped with air and being circulated I wouldn’t have any problems leaving it out for weeks…

Maybe longer…



I would say I leave it out max 2 and a half maybe 3 days…what is all needed with an air stone?

It is just tap water I am leaving out.


Tap is what I use, and it had chlorine that I especially don’t want in my seedlings…

VIVOSUN Air Stone 2PCS 4 X 2 Inch Large Air Stone Cylinder for Aquarium and Hydroponics Air Pump (2PCS 4 x 2 Inch)


Active Aqua Air Pump, 4 Outlets, 6W, 15 L/min


And some hose to connect it to.

Think about an aquarium, now there are charcoal filters in aquariums also, but the main idea to keeping the water usable for an extended period of time is through the use of “bubble stones”.

Aquariums can go months without water changes especially when properly taken care of.



Thanks. I will look into a pump and stone!


@dmykins no problem letting it sit longer but I wouldn’t let it sit long with out moving
what I do is this
I keep a airstone in my water buckets run them 24-7
I also use a cheap fish tank filter to keep water moving
I Picked it all up at Walmart for under $40
The pumps /filters are for a 15gal aquarium
The Air stones will help evaporate the chlorine and filter will keep water Fresh and clean
Hope this helps


If you put bleach in your water it will probably kill your plants. When the chlorine evaporates out from the bleach it leaves sodium hydroxide behind. The pH will be way high! Like 10.


Have you determined whether or not your water treatment facility uses chlorine or chloramine?
The best way to determine the type of chlorine being used in your tap water is to call your water department. You can ask them if they treat your water with chlorine or chlorimide (also called chloramine) which does not evaporate and must be chemically removed.
Tell them you have several large fish tanks you are about to fill up and want to know which one is in your water. They get asked this question often, and know how to answer it. I find if you start talking gardening with them, it often confuses them and they are unsure of how to anwser. If your water ends up having been treated with chlorine, bubbling it for a few hours, will make it more than adequate foruse. If it is treated with chlorimide (also called chloramine), then you can call either a local Pet Store or Swimming Pool Supply Store (usually cheaper than a pet store) and ask about products to remove the chlorimide. The chemical used to do this is called sodium thiosulfate. You can buy it in dry or liquid form.
Once you apply the sodium thiosulfate into your water, using the directions provided on the product label, it will remove the chlorimides within a few minutes. Then bubbling your treated water for 2 hours removes most the sodium thiosulfate, since it’s chemical bonds weaken quickly after reacting with the chlorimides.
You want to remove the sodium thiosulfate since it’s salt that will harm your plants.
The trace amounts of sodium thiosulfate that remain after treatment, are low enough that it won’t harm plants.
Plants treat this chemical as an ammonia element and expel it quite easily. In the soil, bacteria will actually feed on it. That action in turn, helps free other insoluble elements bound in your soil.



I can see a water quality report and it looks as though chloride is listed…


@dmykins a decent water filtration will remove chlorine as well but a RO system would be best
I have well water so the Clorine isn’t a issue for me
They do sell small Ro systems on Amazon but they aren’t the cheapest maybe 4-500
But for long term use might be worth the investment imo


Chloride would be added for the perceived dental health benefit to the municipality’s residents.

Call the water department and ask them whether or not they use chlorine or chloramine.

If they use chlorine then simply bubble it off as the others have instructed.

If they use chloramine then follow the instructions I’ve given you.:slightly_smiling_face:


Clorine is added to kill of bacteria @Alton66
Fluoride is added for perceived dental benefits
Glad I’m on well water :+1:


I agree that bubbling would allow water to sit longer, also agree that if you are bubbling it doesn’t require to be bubbled as long as just sitting for chlorine removal. The chloramine or however you spell it is a different scenario and requires to be removed another way as stated. To the best of my understanding anyway


As stated your local water Dept should have all this info available on line @dbrn32
And once you know we can advise bestv


I’m good. Just chlorine for me, and I bubble for 3-4 hours, add nutes, bubble overnight, ph, then feed.

I was just seconding what you and @Alton66 were stating.


Jeez I meant fluoride not cloride!!!:joy::joy::joy::joy:

That’s what I get for not getting my sleep.:stuck_out_tongue_winking_eye:

Yes once you know what’s in your water we can advise accordingly.:+1: