DIY Automatic Water Changer
I just setup a 220gal tank and I wanted the maintenance to be as easy as possible; so, I added an automatic water changer to the tank during setup. There are dozens of ways to do this, some easier, some cheaper and some probably better; below is how I chose to do it. I was also fortunate enough that my tank is built into the wall backing to an unfinished laundry room. The total cost was around $750, this design could be modified to be done much, much, much cheaper. At any rate, it should serve to give others ideas how to build one.
Requirements
I had several requirements for the water changer:
All of these are not 100% fool proof
Operation
60 gallons changed once a week start to finish 40 minutes. (Can be adjusted from 1-110gallons, 1-7 days a week, as needed per bio-load) The below times were chosen because this is when I'm home and likely to be near the tank in the event of failure.
I just setup a 220gal tank and I wanted the maintenance to be as easy as possible; so, I added an automatic water changer to the tank during setup. There are dozens of ways to do this, some easier, some cheaper and some probably better; below is how I chose to do it. I was also fortunate enough that my tank is built into the wall backing to an unfinished laundry room. The total cost was around $750, this design could be modified to be done much, much, much cheaper. At any rate, it should serve to give others ideas how to build one.
Requirements
I had several requirements for the water changer:
- Completely automated
- Scalability - the ability to adjust the amount and frequency of water removed
- Safeguard concerns for the fish and my house:
- Temperature
- Chlorine
- Completely draining the tank
- Flooding my house
- Drain Pump - Rainbow Quite One 1200
- Shut-off valve (2) ½ ASCO Series 8210 120v
- Mixing valve ¾ Watts L1170-UT M2 Threaded Lo-Temp Mixing Valve
- JBJ ATO Controller
- AquaController Jr
- Timer (2) Intermatic 7-day 7-event digital heavy duty timer
- Plumbing (various)
All of these are not 100% fool proof
- House water is plumbed directly to the sump. Hot and cold water are mixed with a temperature mixing valve to keep the incoming water temp consistent with tank water temp. AuqaController gives Temp and PH readings. Picture 1
- The chlorine from my house is very lower (nearly undetectable with hobbyist test kits). The filtration specialist at the Baltimore National Aquarium told me that based on the amount of water Im changing chlorine will not be an issue. Still being the nervous type, the fresh water gets added to the sump directly on top of the pump that feeds my UV sterilizer. Also, plenty of aeration while the water falls from the sump returns back into the tank.
- The drain pump sits in the tank about 8 below the water line. There is a tube connected to in that runs behind the background that will not allow the tank to drain more than 55%. Shut-off valve on drain pipe stops any siphoning of the tank and any backwash from the house drain line.
- The most troublesome and least secure of my setup is protecting my house from flooding. The clean water is controlled by a float switch on the JBJ ATO; while draining, the sump pump is shut-off after the tank level has dropped below the overflow. This is to keep the sump from completely draining to leave enough water to flow through the fluidized sand filter, as well as keeping the sump pump from running dry. The JBJ ATO is only given power for 20 minutes to lessen the damage if the float switch were to fail.
Operation
60 gallons changed once a week start to finish 40 minutes. (Can be adjusted from 1-110gallons, 1-7 days a week, as needed per bio-load) The below times were chosen because this is when I'm home and likely to be near the tank in the event of failure.
- 1:00am circulation pumps turn off (AuqaController) Picture 2
- 1:00am drain pump turns on and drain pipe shut-off valve opens (Intermatic 7-day timer) Picture 3, 4 and 5
- 1:04am Sump pump turns off (Intermatic 7-day timer)
- 1:20am drain pump turns off and drain pipe shut-off valve closes (Intermatic 7-day timer)
- 1:20am JBJ ATO Controller is powered on (AuqaController), float switch (connected to JBJ ATO) in sump opens shut-off valve on house water (Its allowed to power on daily if needed for evaporation, this works well since the AquaController doesnt do 7-day programming) Picture 6, 7 and 8
- 1:21am Sump pump turns on
- 1:40am JBJ ATO Controller is powered off (tank fills in 15min, float switch in sump shuts off water when tank and sump have been filled)
I can make more money, but not more time! There is also the enjoyment of designing and building it. I enjoy my fish tanks but I don't want to spend hours and hours working on them every week. I've just cut a huge chunk out of my maintenance time. It'll never be maintenance free but it's about as close as it can get - as far as I know. If I could figure out a way to clean the gravel and filter automatically I would 
Any one have idea's?
