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Pond Dechlorinator: How to Dechlorinate Water for a Pond

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Chlorine is a chemical that keeps our drinking water free of harmful bacteria, thus making it safe for us to drink.

But, chlorine in our pond is a different story! It can cause nasty burns and even death to your pond fish…

And it can kill off good bacteria and other forms of aquatic life causing major issues to your pond’s ecosystem.

So, let’s learn how to effectively dechlorinate water for a pond and ensure your pond stays as healthy as possible.

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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.

Digital ppm Tester + Watersafe City Home Tap Drinking Water Test Kit

Digital ppm Tester + Watersafe City Home Tap Drinking Water Test Kit

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

API Pond Master Water Test Kits

API Pond Master Water Test Kits

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While we 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.

Digital ppm Tester + Watersafe City Home Tap Drinking Water Test Kit

Digital ppm Tester + Watersafe City Home Tap Drinking Water Test Kit

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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.

API Pond Master Test Kits

API Pond Master Test Kits

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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.

did you know Important

This is an effective and free option for removing chlorine, but keep in mind, this only works for removing chlorine. It does not remove chloramine!

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.

Pros

  • Effective at removing chlorine
  • Free method

Cons

  • Must wait a few days before you can add water to your pond
  • Does NOT work to remove chloramine
  • Should still use a dechlorinator or test the water before adding to your pond

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!

Seachem Pond Prime Water Conditioner

Seachem Pond Prime Water Conditioner

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Pros

  • Effective pond chlorine remover. A good pond water conditioner will also remove chloramine and potentially other harmful substances like nitrites and ammonia
  • Can be used for new ponds and/or water changes
  • Easy to use. Simply pour the recommended amount of product directly into the pond or into a bucket full of tap water (to condition water before adding to a pond)

Cons

  • If using the recommended pond dechlorinating product above, there really are no cons, other than having to pay for a product

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!

Boogie Blue PLUS High Capacity Tap Water Filter

Boogie Blue PLUS High Capacity Tap Water Filter

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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.

Boogie Blue PLUS High Capacity Tap Water Filter

Boogie Blue PLUS High Capacity Tap Water Filter

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Pros

  • A convenient way to fill or top off a pond
  • A quality product like the one above will remove chlorine, chloramine and other harmful substances
  • Also works well for garden water, pool water, etc.

Cons

  • We recommend testing your water's chlorine levels if using this method to fill a large pond (especially if you're stocking it with koi or other fish)

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)
CrystalClear Polish Activated Carbon

CrystalClear Polish Activated Carbon

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Pros

  • Great for keeping your pond water free from chlorine, chloramine, ammonia, tannins, and bad odors
  • Effectively reduce chlorine levels in new ponds
  • Hands-off solution. Just add carbon filter to your filter box and let it do its work

Cons

  • Not ideal for removing chlorine from tap water when topping off existing ponds with koi or other fish