Automatic Water Change Setup

The friendliest place on the web for anyone with an interest in aquariums or fish keeping!
If you have answers, please help by responding to the unanswered posts.


Aquarium Advice Freak
Nov 8, 2013
I have a 36G freshwater tropical tank. I'm engineering an Automatic Water Change setup and would like your feedback before I purchase anything.

(Yes, gravel and other cleaning will be needed I know, and yes, I'm this lazy to not want to do manual water changes lol)

The main idea: automatically perform 25% water changes every 2 days. Have a reservoir tank in the basement (directly below 1st floor fish tank) that is heated and dechlorinated. An automatic water changer pumps water up to main fish tank, and pumps water down into basement floor drain. Reservoir tank is auto-refilled using a float valve.

  • 25% water change every 2 days
  • 40g long reservoir tank in the basement (thought: 40g long since a 25% water changes requires 9g, and this will make sure the float valve works as intended)
  • Auto doser of water conditioner once/48 hours after the water change (moving water dissipates chlorine in 1-5 days, tho chloramine is still present)
  • Heater
  • Bubbler or circulation pump to keep water oxygenated (circulation pump might become exposed during a water change??)
  • Topping off the reservoir tank: Mechanical float valve
  • Overflow hole (cut in reservoir tank above the float valve) drains to basement floor drain if the float valve fails
  • With the X2SR, set it to water in and out of the fish tank at the same time (so that the fish tank filter's outlet and heater stay submerged and doesn't need to be turned off)
  • A check valve on the in and the out lines prevents siphoning

Things to do/buy:
  • X2SR automatic water changer
  • 2 check valves
  • Strong storage shelf that can store at least the reservoir tank and a hospital tank: 500lbs each shelf
  • 40g long tank
  • Must have wall thickness of ¼" or more to support the float valve
  • Heater for reservoir tank
  • Bubbler or circulation pump for reservoir tank
  • Auto doser Kamoer X1 Pro Pump
  • Auto dosing container
  • Float valve
  • Diamond coated glass drill bits for reservoir overflow hole drain, AND for float valve
  • Sharkbite fitting from cold pex line to reservoir's float valve
If you have chloramine, you need to address that, not just the chlorine. It was explained to me that Chlorine is bonded to ammonia to create chloramine (that prevents the chlorine from evaporating) so unless that bond is broken, neither chemical should be addressed singularly. ( For example, chlorine remover will not remove the chlorine portion of chloramine and just leave the ammonia.)

Another issue may come from the float valve. If the water level goes down due to evaporation, the float valve will add water but if your chloramine remover isn't activated, that could lead to a problem, especially is you have sensitive fish.

If I may suggest, get yourself a 55 gallon plastic drum ( or some other cheap large water receptacle to hold water) that has already been dechloramined and run your float valve from that. This way, you won't have to worry about the chemical parts of the water change, you'll only need to address the water in the drum maybe once a week or so and if you just run an airstone into it, the water will be oxygenated as well. (y)
Auto change system is something I would love, but due to the complexity in my home for the water reserve, that hasn't happened for me. I love seeing others ideas though.

If you look into SW tank auto top off units, many have electronic eyes for the water, and safety alternative eyes to make sure it goes up and down the correct amount.

Not sure how much they cost and would of course would review "problems with..." unit to make sure what you would be getting into.

Andy brings up some very smart points.

Edit: This is the one I was thinking of 2nd edit: this has a 7.2 foot max head height, and that probably would not work from floor below, oops, sorry.
Last edited:
Thank you both!

Full speed ahead on this auto water change idea. I'll post updates once it's built, but most of the components have been ordered :) Here's to hoping an idea pans out ;)
Top Bottom