Gang,
Several people have requested that I do a write-up for my DIY ATO system. Unfortunately, I didn't take many photos during the actual construction of the system, so I don't have step-by-step images. But, I do have photos of the finished product and will be happy to fill in any of the details if anyone decides to put one together.
As we know, there are many ways to facilitate an ATO system - and each seem to have many pros and cons. When I set out to build my ATO, I had the following objectives in mind:
1. It had to be automatic - requiring virtually no interaction on my part.
B. It had to be reliable - since I don't like replacing burned-up pumps when the sump runs dry or using my wet/dry vac to suck up a flood.
3. It had to be invisible - my reef tank is in my living room and I would like it to blend seamlessly into the room (all of my DIY projects have been significantly focused on this goal.)
FOUR. It had to keep the reef happy (isn't that the ultimate goal?)
I have a 100GPD RO/DI system that I use for drinking (RO) and reefing (DI). The pressure tank associated with the RO/DI system stores RO water on tap at the sink. The DI water is generated from this supply as it passes through the DI resin. Thus, the first order of buisness was to create a DI reservoir.
I ran 1/4" tubing from the RO/DI unit to a 7-gallon bucket housed in a cabinet beside the reef tank (my reef is only 30 gal display + 15 gal sump, 7 gallons is plenty for my ATO). I installed a USplastics.com float valve in the side of the 7 gal bucket by simply drilling a hole of the prescribed size. See image below:
As you will see, the top-off water is fed to the sump via a powerhead. You can the powerhead installed in the bottom of the bucket. The plastic tubing is obviously to direct the pump's output to the sump (be sure you don't put the end of the line below the surface of the water in the sump - you don't want to create a syphon when the pump turns off after topping off!)
Thus, I have a constant 7-gallon supply of DI water. The RO/DI system does not run constantly since it fills the bucket to the level determined by the float valve and the flow ceases.
Next, I installed two float switches into the sump (in the return section - where one sees fluctuations in level due to evaporation). The float switches were obtained on eBay for approximately 2$ each. The lower switch is the "low-level" switch that will activate the ATO system. The upper switch is the "high-level" switch - which will be used to signal the ATO system that the sump is full. Of course, placement of the float switches will be determined by the acceptable "low-level" and "high-level" for your sump. I ran the leads from each of the float switches to the area where I would install the control box - the "brain" of the ATO system.
The "brain" of the ATO system is a latching relay. I selected a 5A, 120VAC dual-12VDC-coil, DPST latching relay (digikey.com part no. 255-1056-ND, 7$). This relay will easily handle the amperage draw from a small powerhead (there are cheaper relays that will handle less current - select appropriately). The dual-coil arrangment allows for "set" and "reset" signals - which, as you will see, are provided by the float switches in the sump. I chose 12VDC coils since that is the DC power supply I use to power other items in my reef control system. However, if you aren't currently using DC power, you can grab any old "wall wart" type DC power supply and select the relay coil voltage to match what you can get your hands on. The DPST switching arrangment is necessary if you have a GFCI installed on the circuit to power the pump (you must switch both the hot and neutral AC lines, as I will explain).
To complete my system, I obtained:
1. A standard 120VAC outlet (2$, Home Depot)
2. Miscellaneous hardware (screws, nuts, nylon spacers - 3$, Home Depot)
3. A plastic project box (6$, Radio Shack)
4. A project board (2$, Radio Shack)
5. IC socket (1$, Radio Shack)
6. 120VAC three-prong plug/wire (2$, Radio Shack)
You will also need wire, solder and a soldering iron.
The rest of the construction is wiring the circuit and fitting the above to the project box.
The circuit is relatively simple:
The low-level float switch is wired to the "set" coil of the latching relay. (See DigiKey datasheet)
The high-level float switch is wired to the "reset" coil of the latching relay.
Essentially, the float switches complete a 12VDC circuit (DC+ -> float switch -> relay coil+ -> relay coil- -> DC-).
The hot and neutral leads feeding the AC outlet are soldered to the normally open pins of the latching relay.
The hot and neutral leads from the 120VAC three-prong plug are wired to the supply pins of the relay. (Again, see DigiKey datasheet).
It is important to switch the hot and neutral AC lines at the same time if you are using GFCI - otherwise, the GFCI will trip everytime the relay switches.
Thus, when the "set" coil is energized by the low-level float switch, the relay latches and closes the AC circuit (energizing the AC outlet). The outlet will remain powered until the "reset" coil is energized by the high-level float switch. Viola - ATO.
With the wiring complete, as shown in the photo below, I used nylon spacers to mount the project board and AC outlet on a small piece of acylic - which was then fastened inside the project box:
I then cut openings for the AC outlet in the aluminum cover for the project box - makes everything nice and neat:
Like anything else, there are "failure modes". In my system, the two components that I worry most about are the float valve in the 7-gallon bucket and the high-level float switch. If either get "stuck", you will have a flood. You could always install redundant high-level switches in the sump - it adds to the wiring confusion, but will virtually eliminate the potential for a stuck high-level switch. Like anything else, I think proper maintenance will help to prevent any mishaps.
I hope this was useful (and complete!). I'm here to help if I can.
Jeff
PS> Please excuse any blatant spelling or grammatical errors!
Several people have requested that I do a write-up for my DIY ATO system. Unfortunately, I didn't take many photos during the actual construction of the system, so I don't have step-by-step images. But, I do have photos of the finished product and will be happy to fill in any of the details if anyone decides to put one together.
As we know, there are many ways to facilitate an ATO system - and each seem to have many pros and cons. When I set out to build my ATO, I had the following objectives in mind:
1. It had to be automatic - requiring virtually no interaction on my part.
B. It had to be reliable - since I don't like replacing burned-up pumps when the sump runs dry or using my wet/dry vac to suck up a flood.
3. It had to be invisible - my reef tank is in my living room and I would like it to blend seamlessly into the room (all of my DIY projects have been significantly focused on this goal.)
FOUR. It had to keep the reef happy (isn't that the ultimate goal?)
I have a 100GPD RO/DI system that I use for drinking (RO) and reefing (DI). The pressure tank associated with the RO/DI system stores RO water on tap at the sink. The DI water is generated from this supply as it passes through the DI resin. Thus, the first order of buisness was to create a DI reservoir.
I ran 1/4" tubing from the RO/DI unit to a 7-gallon bucket housed in a cabinet beside the reef tank (my reef is only 30 gal display + 15 gal sump, 7 gallons is plenty for my ATO). I installed a USplastics.com float valve in the side of the 7 gal bucket by simply drilling a hole of the prescribed size. See image below:
As you will see, the top-off water is fed to the sump via a powerhead. You can the powerhead installed in the bottom of the bucket. The plastic tubing is obviously to direct the pump's output to the sump (be sure you don't put the end of the line below the surface of the water in the sump - you don't want to create a syphon when the pump turns off after topping off!)
Thus, I have a constant 7-gallon supply of DI water. The RO/DI system does not run constantly since it fills the bucket to the level determined by the float valve and the flow ceases.
Next, I installed two float switches into the sump (in the return section - where one sees fluctuations in level due to evaporation). The float switches were obtained on eBay for approximately 2$ each. The lower switch is the "low-level" switch that will activate the ATO system. The upper switch is the "high-level" switch - which will be used to signal the ATO system that the sump is full. Of course, placement of the float switches will be determined by the acceptable "low-level" and "high-level" for your sump. I ran the leads from each of the float switches to the area where I would install the control box - the "brain" of the ATO system.
The "brain" of the ATO system is a latching relay. I selected a 5A, 120VAC dual-12VDC-coil, DPST latching relay (digikey.com part no. 255-1056-ND, 7$). This relay will easily handle the amperage draw from a small powerhead (there are cheaper relays that will handle less current - select appropriately). The dual-coil arrangment allows for "set" and "reset" signals - which, as you will see, are provided by the float switches in the sump. I chose 12VDC coils since that is the DC power supply I use to power other items in my reef control system. However, if you aren't currently using DC power, you can grab any old "wall wart" type DC power supply and select the relay coil voltage to match what you can get your hands on. The DPST switching arrangment is necessary if you have a GFCI installed on the circuit to power the pump (you must switch both the hot and neutral AC lines, as I will explain).
To complete my system, I obtained:
1. A standard 120VAC outlet (2$, Home Depot)
2. Miscellaneous hardware (screws, nuts, nylon spacers - 3$, Home Depot)
3. A plastic project box (6$, Radio Shack)
4. A project board (2$, Radio Shack)
5. IC socket (1$, Radio Shack)
6. 120VAC three-prong plug/wire (2$, Radio Shack)
You will also need wire, solder and a soldering iron.
The rest of the construction is wiring the circuit and fitting the above to the project box.
The circuit is relatively simple:
The low-level float switch is wired to the "set" coil of the latching relay. (See DigiKey datasheet)
The high-level float switch is wired to the "reset" coil of the latching relay.
Essentially, the float switches complete a 12VDC circuit (DC+ -> float switch -> relay coil+ -> relay coil- -> DC-).
The hot and neutral leads feeding the AC outlet are soldered to the normally open pins of the latching relay.
The hot and neutral leads from the 120VAC three-prong plug are wired to the supply pins of the relay. (Again, see DigiKey datasheet).
It is important to switch the hot and neutral AC lines at the same time if you are using GFCI - otherwise, the GFCI will trip everytime the relay switches.
Thus, when the "set" coil is energized by the low-level float switch, the relay latches and closes the AC circuit (energizing the AC outlet). The outlet will remain powered until the "reset" coil is energized by the high-level float switch. Viola - ATO.
With the wiring complete, as shown in the photo below, I used nylon spacers to mount the project board and AC outlet on a small piece of acylic - which was then fastened inside the project box:
I then cut openings for the AC outlet in the aluminum cover for the project box - makes everything nice and neat:
Like anything else, there are "failure modes". In my system, the two components that I worry most about are the float valve in the 7-gallon bucket and the high-level float switch. If either get "stuck", you will have a flood. You could always install redundant high-level switches in the sump - it adds to the wiring confusion, but will virtually eliminate the potential for a stuck high-level switch. Like anything else, I think proper maintenance will help to prevent any mishaps.
I hope this was useful (and complete!). I'm here to help if I can.
Jeff
PS> Please excuse any blatant spelling or grammatical errors!
