Pond Dechlorinator: How to Dechlorinate Water for a Pond

by Tory Jon | Last Updated: December 07, 2020

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Can I Use Tap Water In My Pond?

Yes, you can use tap water in a pond, but only if it’s been properly dechlorinated.

As we discussed above, chlorine can be harmful, and even fatal, to aquatic life and cause all sorts of issues for your pond’s ecosystem, including:

• Killing of good bacteria: Chlorine is highly effective at killing bacteria in our drinking water. And while that’s great news for us, it’s terrible news for your pond. Chlorine can’t tell the difference between good and bad bacteria, so it essentially kills ALL of the bacteria. Without beneficial pond bacteria, your ponds water quality will drastically drop, waste will rapidly grow, and your pond will have noticeable aesthetic issues, as well.
• Fish burns: Chlorine is highly toxic to koi and other fish, and can cause burns to their gills, scales and breathing tissue.
• Fish poisoning & death: Along with causing painful burns to your pond fish, chlorine can also cause poisoning and death. Koi chlorine poisoning symptoms include paleness, erratic behavior, and may even cause red spots and mucus to appear on their body.

Pretty much all tap water has either chlorine or chloramine (a mix of chlorine and ammonia) in it.

You can contact your local water supplier to see exactly which chemical they use, or you can test your tap water for chlorine and chloramine.

You can use this electronic tester to see if your tap water has chlorine.

You’ll also need to test for ammonia since a simple chlorine test won’t identify if it’s chloramine in your tap water.

While I recommend you have the above kits for testing your tap water before adding it to your pond (even after you treat it to ensure it's safe), we always simply assume both are in the water and treat it for both.

What Level Of Chlorine Is Safe For Pond Fish?

The ideal level of chlorine in your pond water is 0.00 PPM (Parts per Million).

Chlorine provides zero benefits to your pond so there should always be as close to none as possible in your water.

Of course, that’s the ideal level of chlorine. In reality, if you live in a hot climate and have to top off your pond's water regularly, it can be hard to keep it at 0.00 PPM all the time. So, just try to keep as close to 0.00 PPM as possible.

If you’re concerned your pond might have higher levels of chlorine than it should, you can always test your water.

And, again, don’t forget to test for ammonia levels, as well, if you’re not sure whether your water supply has chlorine or chloramine in it.

How To Dechlorinate Tap Water For A Pond

So, let's learn how to remove chlorine from water for fish health and safety. And for the safety of your pond’s ecosystem.

Let Tap Water Stand

Before adding tap water to a koi pond, or any backyard pond for that matter, you can fill up a bucket and let it sit out. Chlorine will naturally rise to the surface of the water and escape into the atmosphere.

If you know your water has chloramine in it, you’ll have to refer to one of the options below to dechlorinate your pond water.

So, how long before tap water is safe for pond fish. You’ll need to let the bucket of water sit out for at least 48 hours before testing it. I’ve read claims of 24 – 48 hours it should be free of chlorine, but having tested tap water using this method, we’ve found it can take longer. So, wait at least 48 hours, and preferably longer.

This isn’t an exact science, and unless you test the water, you won’t be sure that its chlorine levels have dropped enough to be safe for your fish. For this reason, we still recommend you use a dechlorinator/conditioner, which we’ll cover next, or test your water.

Pond Dechlorinator & Conditioner

Pond water dechlorinator can be used as a new pond water treatment or to remove chlorine from tap water during water changes. It also removes other contaminants like chloramine and nitrites, so even if you let your pond water stand for a day or two before adding it to your pond, it’s still a good idea to use a dechlorinator.

Be sure to choose a pond chlorine treatment that removes both chlorine and chloramine. One of the best pond dechlorinator products on the market is Pond Prime, which removes chlorine, chloramine, ammonia, and nitrites!

Carbon Filter Hose Attachment

A convenient way to dechlorinate tap water while filling or topping off your pond is to use a carbon filter hose attachment.

The carbon filter attachment screws right on to any standard ¾” garden hose and dechlorinates the water as it passes through the filter.

The Boogie-Blue Plus Filter removes 99% of chlorine, 87% of chloramine, and reduces heavy metals and pesticides. It can also filter up to 45,000 gallons of water!

You could effectively top off your pond (literally thousands of times) using this attachment. If you are filling a pond with it, I’d personally still test the water to be sure the chlorine/chloramine levels are acceptable.

Also, when purchasing any carbon hose filter product, make sure it’s safe to use for pond water. Many carbon fiber hose attachments have not been tested for pond use. However, the Boogie-Blue Plus is one of the few attachments that claims it can be used for pond water.

Here’s a short video with more information about the Boogie-Blue Filter.

Activated Carbon Filter Media

Another option to remove chlorine from a pond is using activated carbon filter media. This is simply activated carbon that sits in your pond filter box.

Essentially, carbon uses a process called adsorption which removes contaminants from pond water by making them stick to it. So, as the pond pump circulates water through your filter, harmful contaminants stick to the activated carbon filter media, then are manually removed when you replace the media (about every month or so).

This method is effective for:

• Continually keeping your ponds chlorine and chloramine levels in check
• Helping bring chlorine levels down to acceptable levels after filling a new pond (and before adding koi or other pond fish)