How to Build an Automatic Aquarium Water Changer

Removing existing aquarium water and adding freshly prepared water helps dilute harmful chemicals, such as nitrate and phosphate, and replenish trace minerals. For best results, you should change 20 percent of the total water volume of the aquarium every week. This means if you have a 50 gallon aquarium, you should replace 10 gallons of aquarium water with freshly prepared water every week. The freshly prepared water should at least be dechlorinated, and filtered water is generally better. Setting up a system to automatically change the water takes some effort. If you have a continuous supply of fresh water, this setup only works for freshwater systems.

Things You'll Need

  • Overflow box
  • PVC pipe
  • Saddletap valve
  • Icemaker plastic tubing
  • Inline water filter
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Instructions

  1. Constructing the Waste Water Plumbing

    • 1

      Add an overflow to the aquarium. You can make an overflow from PVC or use a box overflow if you are unsure how to construct one yourself. You want the water to flow into the overflow pipe when the water level in the aquarium reaches a certain height.

    • 2

      Plumb the overflow to a wastewater drain. Wastewater from a freshwater aquarium can be drained onto the lawn or a garden. Since it is wastewater, you can use whatever plumbing you need to make it work: PVC, flexible tubing or copper tubing.

    • 3

      Test the overflow system by adding several gallons of freshly prepared water. As you add the new water, the old water should top the overflow and flow down the drain. Check for leaks in the plumbing and make sure the water does not top the aquarium itself. To be safe, leave about a half- to quarter-inch clearance between the maximum height of the water and the top edge of the aquarium.

    Constructing the Fresh Water Intake

    • 4

      Tap your freshwater supply for your house with a saddletap valve. These valves work by latching on and puncturing a hole in a copper pipe. Tap the pipe in a safe place and do not tap into the hot water supply. If your house uses a water softener, tap the water before it enters the softener system.

    • 5

      String a hose from the tap to the aquarium. To be safe, use plastic icemaker hose rather than copper. Copper hose has the potential to leach copper into the aquarium, which can kill invertebrates.

    • 6

      Install a water filter between the aquarium and the freshwater tap. You can purchase filters for icemakers filled with granular activated carbon (GAC) and sometimes deionizing resin. GAC will remove chlorine from the water as well a many other chemicals. Deionizing resin will help remove heavy metals such as aluminum that can be harmful to your fish. Instead of the GAC filter, you can also use a reverse osmosis filter.

    • 7

      Turn on the saddletap until you get a fast drip from the tubing into the aquarium or the aquarium sump. Install the freshwater drip on a different side than the wastewater overflow so the water has a chance to mix with the aquarium water.

    • 8

      Turn on the system and watch it carefully. First, check to be sure the saddletap isn't leaking. Then check the connections to the filter and make sure they are dry and tight. Next, check the drip line into the aquarium and make sure it is secure and does not have the potential to fall onto the floor. Check the level of the water in the aquarium and make sure it is flowing into the overflow and down the drain pipe. Let this run for at least a full day, checking it frequently, to be sure everything is working and not leaking.