How to Prepare Freshwater Aquarium Water

Water companies add chemicals such as chlorine and chloramine to a domestic water supply to make it clean and safe to drink. These chemicals are harmful to tropical and coldwater fish, so you must adapt the chemical makeup of your tap water before pouring it into a freshwater fish tank. A broad-spectrum dechlorinator solution neutralizes chemical deposits, and a beneficial bacteria booster increases the filter's ability to process fish and plant waste. Prepare new tank water in a bucket, and adjust the temperature according to your fish's requirements, before adding it to your aquarium.

Things You'll Need

  • Floating aquarium thermometer
  • Bucket
  • Tap water
  • Water dechlorinator
  • Beneficial bacteria solution
  • Saucer
  • Jug
  • Aquarium water pH test kit
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Instructions

    • 1

      Mix the dechlorinator with half a bucket of water, according to the manufacturer's dosage instructions. Some brands only require a couple of drops per bucket of water, and others need significantly more, so read the guidelines carefully if you are unfamiliar with the product, because some commercial dechlorinators are highly concentrated. Always pour the dechlorinator into the bucket before adding water, to allow the solution to dissolve efficiently and evenly.

    • 2

      Place a floating thermometer in the bucket when it is approximately half full of water. If you are carrying out a partial water change, the new water's temperature must be the same as the existing tank water to avoid causing your fish stress. Top up the bucket with warm or cold water until it matches your tank temperature. As a guide, the acceptable temperature for tropical fish is between 77 and 80 degrees Fahrenheit, and 68 to 75 degrees for coldwater fish.

    • 3

      Check dosage instructions and add the beneficial bacteria booster to your bucket of water. Stir through. Pour the prepared water into your aquarium with a jug. For a new tank setup, place an upturned saucer in the bottom of the tank and trickle the water over it to avoid disrupting gravel and tank decorations. A large flat rock is an effective alternative to allow the water to dissipate gently over the substrate.

    • 4

      Test your water with an aquarium pH test kit to determine how acidic (soft) or alkaline (hard) your tap water is. PH measures the acidity or alkalinity of water on a scale of 0 to 14. A pH of 7.0 is neutral and different species of freshwater fish have specific pH requirements, but most community freshwater fish are happy in a pH range of 6.5 to 7.5.

    • 5

      Choose your fish according to your water's natural pH level or make slight adjustments with natural materials if you do not want to tamper with your water chemistry. If you have high pH readings, add a piece of driftwood to hard water to lower pH gently and increase acidity. Raise pH and alkalinity by adding crushed coral or seashell to your substrate in soft water.

    • 6

      Install a filter system appropriate to the volume of your fish tank. Filters have different operating capacities, and a large, heavy-duty filter is better than one too small for the job. Manufacturer's guidelines indicate the maximum tank size suitable for each filter in their range. If you are unsure, or your aquarium volume is between two filter sizes, choose the larger capacity filter to keep your water clean and healthy.