SESKStuff Everyone Should Know
SESK: Stuff Everyone Should Know · sesk.info/fish-fill-tank-before-plugging-in

Setting up a new tank: when should the filter, heater and pump be turned on?

Only after the tank is filled with water.

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  1. Before any water goes in
  2. Whenever, it does not matter
  3. Only after the tank is filled ✔

Why: Merck says filters, pumps, heaters and lights should not be turned on until the tank is filled. Many aquarium electronics, especially submersible pumps, need the water to keep them cool and running safely.

Huh, didn't know that: Merck says to check that the outlet near the tank is grounded and has a GFI, and to consider a surge protector.

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References

Answer: Only after the tank is filled. Merck says filters, pumps, heaters and lights should not be turned on until the tank is filled. Many aquarium electronics, especially submersible pumps, need the water to keep them cool and running safely.

  1. Merck Veterinary Manual: Providing a Home for Fish www.merckvetmanual.com/all-other-pets/fish/providing-a-home-for-fish
    Filters, pumps, heaters, and lights should not be turned on until after the tank is filled with water.
    Checked 2026-10-11.

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