For Koi Keepers whose water supply is from a municipal water department, chlorine (and its deadlier cousin chloramine) is a fact of life. To successfully keep Koi, you will need to successfully manage chlorine.

Every scientific study conducted on chlorine and fish has concluded that moderate levels of chlorine can quickly kill most fish. These studies have also shown that prolonged exposure to even miniscule amounts of chlorine result in serious health problems.

The commonly accepted method for dealing with chlorine is to simply apply a little dechlor to the pond before turning on the hose. If there seems to be a problem, add some more dechlor.

I hope that I can convince you to relegate this practice to the same distant heap with other poor methods of old like blood letting. So, before exploring a new method, what's wrong with the standard practice? Many things including:

-Under the best circumstances, you're exposing your Koi to a brief period of chlorine. Repeated exposure to chlorine is harmful to your Koi. Unfortunately, there is no easy way to see what harm is done in these chlorine exposures, so we are lulled into thinking that there is no problem.

-All too often, the hose gets left on and your Koi get exposed to a lot more chlorinated water than you planned. Using an automatic water timers helps, but these devices are cheaply constructed and are prone to failure.

-In most ponds, the Koi will gather at the hose. They just love that moving water and they don't know they're exposing themselves to untreated chlorine.

-Municipal water chlorine levels are not constant or predictable. While 99% of the time the water coming out of the tap will have a normal dose of chlorine, you need to be prepared to deal with the unexpected surge in chlorine. Chlorine surges may be caused by failures of equipment or operators. Surges may also be intentionally induced to deal with problems such as broken water lines, excessive rain fall, changing weather, etc. Chlorine surges are common enough that they pose a real and significant threat to your Koi.

-Waiting for your Koi to discover problems is effective, but its like testing for land mines by jumping up and down on the area in question. There's a better way to do it.

I've heard many excuses for not improving Koi keeping practices. I hope I can convince you to strive for a better standard of care for your wet pets.

"I don't need to test for chlorine - I always have 1.0 ppm chlorine in my tap water." It must be nice to be clairvoyant and connected to an absolutely flawless water department. I recommend testing for the rest of us.

"If my Koi show a problem, I'll just squirt in more dechlor." Please don't use your living jewels to probe for mines. Even if they survive the experience, they would be in better health if you would have avoided the brief chlorine exposure.

"I can't test for 0.001 ppm chlorine without complicated and expensive equipment, so why bother?" You don't need fancy equipment, just a simple, inexpensive pond grade test kit.

"I just use lots of dechlor, so I don't need to bother with testing." Over dosing with anything is not a good practice. You also don't know how badly your water department may have fowled up today, so it's impossible to know how much dechlor is enough without testing.

So by now you're probably saying to yourselves "Ok Mr. Smarty-Pants, lets hear your wonder method."

The Method:

You need the following: isolated tank, dechlor, chlorine test kit. Depending on the size of your pond, you can make an isolation tank from trash cans (be sure to use clean containers that are dedicated to your pond), 55 gallon barrels, poly tanks (available in many sizes), kiddie pool, inflatable pool, etc. You can buy dechlor from most pet stores or pond suppliers. You can also make inexpensive dechlor from sodium thiosulfate (just mix ST with water - use 10% to 15% ST - 8 ounces ST (about 2 cups) in 2 liters (a pop bottle) is just right). A chlorine test kit is harder to find (you haven't been using them, so the stores have quit selling them). Aquatic Eco-Systems sells a good test kit - the LaMotte kit (part number LM680) is good and inexpensive ($16 for the kit, and just $12 for refills).

Step 1: Fill your isolation tank with fresh water.

Step 2: Treat tank with "normal" dose of dechlor. Using typical dechlor (10% to 15% ST) with typical chlorine (1.0ppm) you need 1ml of dechlor per 10 gallons of water.

Step 3: Mix thoroughly. Use a piece of pipe to manually mix or use a water pump or use an airstone and airpump.

Step 4: Test for chlorine. If the test is negative, go on to step 5. If the test shows even a trace of chlorine, go back to step 2.

Step 5: Add safety dose (1/2 of normal dose) of dechlor. This is done to make sure you're not allowing trace levels to go untreated. With a cheap test kit, trace (i.e. less than can be detected with your test) levels can be significant.

Step 6: Test for other problems (ammonia, low KH, etc.) and treat as necessary. This is a topic for another article (or whole series).

Step 7: Mix thoroughly.

Step 8: Add new water to your pond.

Now, that wasn't so hard was it? You and your Koi should breath easier knowing you've slayed the Chlorine Monster that's lurking in your hose.

Koi