How to Add Water to a Fish Pond: 8 Essential Tips

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If not properly processed or prepared, adding water to a pond can harm, or even kill, the fish that live there.

To add water to a fish pond, you must process the water through a biofilter. The biofilter should be capable of removing both chlorine and ammonia before the water enters the pond. Properly filtering your water is critical for the safety of the fish.

There are a number of vital steps that you must take in order to ensure the safety of the water before, during, and after entering it into a fish pond. Read on to learn more about water safety for fish!

Understanding Your Pond

It is important to first note how much water your pond can hold. For example; A woman in Louisiana was searching to find a way to safely fill her fish pond with city water.

She quickly discovered that the greater the amount of water there was within her pond, the greater the amount of city water could be directly added into the pond.

She had a fourteen hundred gallon pond, which she would refill with about one hundred to two hundred gallons of water over the summer. However, within the size of a fourteen hundred gallon pond, an amount of 200 to 400 gallons of city, or chlorinated water, can be added to the remaining water without causing any harm to the fish.

This led to her understanding that this process was only necessary when adding a greater amount of city water than she had previously done. (Source: How do I add city water w/o killing my fish! – Community Forums)

Being Aware of Your City Water

It is necessary to understand if your city treats their water with chlorine or chloramine. The majority of pond people report that you can safely add city water to your pond as long as you add it slowly. Most limit this to less than 5% of the total pond volume per day, added slowly over several hours.

However, without further understanding the depth and volume of your pond, as well as the chemical concentration of your water, you are at a risk of endangering your fish. The best and safest option, is to filter the water before adding it to a populated fish pond. Disrupting the fish with unfiltered water can kill them as they are unable to survive in chemically treated water.

What to do When Your City Water has high Chlorine Concentration

When using water containing chlorine, a hyper intensive spray will cause the chlorine to gas off quickly, evaporating into the air.

Another available options, is to remove the chlorine by applying pond water conditioner based on a chemical called sodium thiosulfate.

This may be purchased in liquid form or as crystals, for safe and easy placement into the water. You must mix the conditioner into the water within a container before adding or mixing the chlorinated water into your pond.

However, If you have a small pond and need to perform a small water change, you can simply leave your tap water to stand in a large bucket for 24 hours. This will allow chlorine time to reach to the surface of the water and escape into the atmosphere.

If your City Water has high Chloramine

Some cities add chemicals to our water to clean it, which are poisonous to fish. Adding water straight from your sink or hose is never a good idea, since you don’t really know what you’re exposing your fish to. Chlorine and ammonia are two of the more common chemicals in our housewater.

Water can, however, be treated with a water conditioner to get those chemicals down to far more manageable levels, making it possible to use your tap water for your fish.

Keep in mind that water that has been treated with conditions can not be accurately tested with a Nessler kit, making it harder to get an accurate reading on the chemical composition of your pond. (Source: How do I add city water w/o killing my fish! – Community Forums)

Fairly consistantly, the easiest way to add water to your pond seems to be by using a biofilter.

Preparing The Water For Fish

When preparing the water to enter the pond, you must first verify how much water is needed within the excess space of the pond. The necessary amount will fluctuate throughout the year, particularly during the summer season, when the rate of evaporation increases.

After calculating how much excess water is needed, you must measure the chlorine and or ammonia within the water that you are going to add to the fish pond. Once determining which chemical is in the water, and the level of concentration, you can begin to filter it correctly into your pond.

Installing a Filtered Pump

Adding a whole house water filter with a carbon filter is an easy solution to city water problems. Be sure that you purchase one that will be capable of removing both chlorine and ammonia. However, you may also add a filtered pump to the pond itself by following these steps.

  • Choose the Right Size – A quality pond pump will be equipped with a filter in a container outside the pond itself, which helps to change out the water. Changing the water in the pond essentially refers to the process of cycling the entire pond capacity through the filter, effectively cleaning the whole pond. The average “change rate” you should be shooting for is an average of 5 times an hour.
  • Constructing the Filter Box – Your filter isn’t going to go into the pond itself, so to keep things aesthetically pleasing you can either build some sort of camouflaged container, or hide it using rocks and plants.
  • Connecting the wire – Connect the wire to the electrical box by running wires, through a plastic PVC conduit underground, from the filter to the electrical supply. Using hose clamps you can connect both the inlet hose and the outlet hose, putting both in places where they are going to be hidden from sight.
  • Temporarily remove fish and water – In order to properly install a new filtered pond pump, you must temporarily remove any fish and water to a safe location until the pump can be properly installed.
  • Install Pump – Run water into the pond until the bottom is covered. This will help you get rid of wrinkles in the liner and show you any low spots. After filling in these spots, and fixing your liner, you can place the pump on the bottom of the pond.
  • Connect and fill – Connect the hoses to the pump to send water to the filter, and begin filling the rest of the pond. After the water is finished filling, plug in the pump, and check to see if the water is running freely (without any clogging or suction noises).
  • Add Plants and Fish – Let the pump circulate the water for a few days to get rid of any debris from construction and to check the “change” rate. Once everything is set on the pump and the pool, you may once again add your fish and other biological elements. (Source: Installing a Pond Pump and Filter |

Place the filter into either the pond pump itself or in a place where you are the most likely to gather the water for the pond. As the water filters, be sure to test the chemical concentration levels to ensure that it is safe for use. And, as previously stated, you should have zero readings for chlorine and ammonia.

Using an Inline Filter for Easy Filtration

There are also inline filters that can be hooked to your water hose. As with the carbon or bio filter, be sure that you purchase one that will remove both chlorine and ammonia.

Test the water after filtering to ensure that it is safe for use and, As previously stated, you should have zero readings for chlorine and ammonia before adding the water to your pond.

Verifying that Your Water has been Cleared

Once your pond has been filled to the desired level, ensure that the process has been done correctly by once again testing the chemical concentration within your water. You can purchase pH strips at any store; these determine the level of acidity the water is, or how basic. Knowing the desired pH levels for varying fish helps to keep them safe.

If the concentration level is still high in ammonia or other nitrates, check the filter that you have placed in either your water pump or hose.

If you used an inline filter and the water is still concentrated with ammonia, switch to a biofilter or carbon filter within the pond water pump.

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