Watch Out For Chlorine In Your Fish Pond

I recently came across this post in a pond forum and wanted to share this with you…and while you’d think this would be a rare thing to happen in a fish pond, that’s not really the case.

“Late last fall ,I allowed a distraction to cause me to effectively KILL all  of my Goldfish ,I had just turned on the tap water to add about 50 gals of make up water,company came ,and you know the rest ,5 hrs later ,the massacre was found ,I was SICK ,after the funeral for 85 of our friends.”

If you live in a city and/or use municipally treated water, then you’re facing a challenge of dealing with either chlorine, or worse yet, chloramines, in the water.  These chemicals are commonly used to help disinfect drinking water and while they may not cause any issues for us in the short term, the fact is they are deadly to pond fish.

As I’ve written before, chlorine alone, will generally dissipate pretty quickly.  So let’s say you don’t have any fish in the pond and you’re just starting up for the spring.  If you fill the pond with water and let it sit for a day or two, the chlorine will have evaporated and it should be safe to put the fish in.  

But chloramines are different.  They’re designed to be more long lasting and it can take a week or more for them to drop in a freshly filled pond.  In reality  the only way to test whether the water is safe for fish is with chlorine test strips (much like you would use for a pool) and any measurable reading is probably enough to cause some problems.

If you can, it’s important to contact your municipal water manager and find out if they use chlorine or chloramines so you can plan things out.  

If you find you have a measurable level of chlorine or chloramines, there are dechlorination tablets or liquids you can add to the water to neutralize the chemicals.  Just be sure to remember to do this!

Another option, and the one I prefer to use now is to use a dechlorinating pre-filter on my garden hose.  These take out all the problematic substances and will treat thousands of gallons of water, so they’re good not only for filling the pond in the spring (however be patient-due to the filtering process the flow rate will need to be slower), but also for topping off the water throughout the season.  They make a useful tool for the municipal gardener as well, since chlorine isn’t all that good for plants either.

Regardless of whatever tool or method you decide to use, just consider this a friendly spring reminder to be sure to keep the chlorine and chloramines out of your fish pond at all times. Your fish will surely be grateful for your diligence!