DIY ATO on the cheap! :D

Stella1979 · Jul 24, 2018

Hey there fellow reefers.

So, I am not electrically inclined... at all. Luckily for me, the hubs is (we'll call him J). The following was written by him and I am very proud to share it here with you.

This DIY ATO has been running successfully for a little over two weeks now, and while that is not a terribly long time, salinity has remained perfect and we are very happy with the build so far.

Please let us know what you think.

DIY Optical ATO

The StellATO

First off, I am self-taught, not an electrical engineer. I won't be held responsible for personal/pet/invert/coral harm or property damage. Now that we've got that out of the way, let's get into a little DIY electronics.

Well, after a year of looking at ATO's and considering a build, Stella put on this video to get in my head one day, and it worked! Gotta give credit where it's due, so thank you very much Reef Dudes @shiftline ... if I'm not mistaken.) Seriously, thanks dude.

Ultimately, we knew that we didn't want more equipment visible in our 20g long reef, but optical ATO's from trusted brands are expensive. Plus, there are always those bad reviews and disaster stories about these things failing. So, we wanted an option with as much redundancy as possible and for it to be easily and cheaply serviceable when needed.

This is not my first electronic build, but I would say that this is the most complicated circuit I've built so far.

This project requires soldering electronic components to a PCB(printed circuit board). Soldering irons and kits are pretty cheap and if you are inexperienced there are great videos on Youtube. Practice making simple circuits, like lighting an LED for example.

Anyhow, here we go.

Hardware
Project box(https://www.amazon.com/B0195UQJAU)$7.42
Optical sensors Qty: 2(https://www.ebay.com/itm/153034129330)$5.29 x 2
Mounts for sensors and float switches… diy’d these out of spare acrylic.
Float Switches Qty: 2(https://www.ebay.com/itm/112095617933)$1.14 x 2
Pump(https://www.amazon.com/B01IBKJWNG)$8.99
12V 2A power supply(wall wart)(https://www.amazon.com/B01GD4ZQRS)$7.69
12v Piezo Buzzer(https://www.taydaelectronics.com/buzzer-alarm)$0.56
Red LED(https://www.taydaelectronics.com/red led)$0.02
Connectors: 5.5 x 2.1mm Qty: 2 male, 2 female(https://www.ebay.com)$0.99

Aviation 3-pin Qty: 2 male, 2 female(https://www.ebay.com)$1.73 x 2
Aviation 2-pin Qty: 2 male, 2 female(https://www.ebay.com)$4.99

Circuit
Solderable half-size breadboard(https://ww.amazon.com/B072JXHQGL)$9.88
N-Channel Mosfets IRFZ44N Qty: 3(https://www.taydaelectronics.com/mosfet)$0.45 x3
5V Voltage Regulator 7805(https://www.taydaelectronics.com/lm7805)$0.23
555 timer IC (integrated circuit)(https://www.taydaelectronics.com/ic-555-timer)$0.13
Capacitors: 100uf 16v Qty: 1(https://www.taydaelectronics.com/capacitor)$0.02
.01uf 50v Qty: 1(https://www.taydaelectronics.com/capacitor)$0.03
Resistors: 470 ohm Qty: 3(https://www.taydaelectronics.com/resistors)$0.10
10K ohm Qty: 2(https://www.taydaelectronics.com/resistors)$0.10
220K ohm Qty: 1(https://www.taydaelectronics.com/resistors)$0.10
Diodes: 1N4004 Qty: 3(https://www.taydaelectronics.com/1n4004-diode)$0.02
1N4148 Qty: 1(https://www.taydaelectronics.com/1n4148-diode)$0.01
Relays: 12v SPDT Qty: 1(https://www.taydaelectronics.com/mini-relay-spdt-12vdc)$0.64
5v SPDT Qty: 1(https://www.taydaelectronics.com/mini-relay-spdt-5vdc)$0.62

Total: $60.21

Tools used
Drill
Step drill bit
Soldering iron, Solder, Flux
Wire stripping/crimping tool
Misc. hand tools - screwdriver, pliers, tweezers, etc.

Miscellaneous Materials
Wire - 22 AWG
Butt Connectors (20-24 AWG)
Electrical Tape
Adhesive - hot glue or double sided tape, for attaching the board inside the box.
Wire dressing - split loom, for example

Here’s what I did:

On one long side of the project box, I drilled appropriately sized holes with the step drill bit for the 4 male aviation connectors and installed them. On a short side, I drilled a hole for and installed one female barrel connector. On the other short side, I drilled for and installed another female barrel connector, the red LED which was hot glued in place, as well as a small hole for the buzzer’s speaker and glued it just inside on the inner wall of the box.
Soldered all electrical components to the breadboard, according to the schematic, leaving a few inches of wire hanging out as needed for the connectors, the LED, and the buzzer, (see breadboard image). Sorry guys, this is the fun/hard part that I just can’t list individual steps for.

3. Mounted the circuit board inside the project box using double-sided tape (3M command strips to be precise), or alternatively, a thick layer of hot glue could be used.

4. Soldered wires from the circuit board to the appropriate connectors, LED, and buzzer(according to the schematic and breadboard image) that were previously installed in the box. The single barrel connector on one short side of the box was used for power in, the 3-pin aviation connectors for the optical sensors, and the 2-pin aviation connectors were used for the reservoir’s float switches. The barrel connector on the side of the box with the led and buzzer goes to the pump. I labeled the box for 12v in, sensors 1 & 2, float switches 1 & 2, and pump.

5. Extended wires as needed for the pump and float switches. Attached a male barrel connector to the pump wires. Attached the 2-pin female aviation connectors to the float switch wires. Did not need to extend wires for optical sensors in our setup. Installed the 3-pin female aviation connectors on the optical sensors wires. Labeled all wires appropriately.

6. Made a holder out of acrylic and mounted the pump and float switches on it. For the upper float switch, the one that turns on the red led, I had to remove the clip and flip the float over in order to make it an NC (normally closed) switch. That way when the float goes down, the led turns on.

7. Attached a hose and put it all in the reservoir. Ran the hose to the tank and held it in place with a binder clip next to a powerhead.

8. Mounted the optical sensors in the tank on a piece of acrylic glued under the rim of the frame.

9. Mounted the box on the wall, ran wires, and plugged everything in. We dressed up the wires with split loom, zip ties, etc. (optional).

There is a delay in the circuit that waits until the sensor is not touching water for 24 continuous seconds in order to keep the pump from short cycling due to water movement. Then, water pumps until the first sensor touches water and stops. If the first sensor fails and does not stop the pump, the second sensor stops the pump when water touches it and sounds the buzzer. When the reservoir is low, the upper float switch triggers the red led on the control box to light up. When the reservoir is empty, the lower float switch will trigger and the pump will not run, so the system is disabled until the reservoir is refilled.

Antics · Jul 24, 2018

I'll never try it... But this kind of content is excellent! Its awesome how much information is freely shared on R2R to help others out. Thanks for the write up!

ramona · Jul 24, 2018

Awesome!
Now, only if I could find someone that understands the language....

RichtheReefer21 · Jul 24, 2018

That is a sweet project sir... I work hands-on in electronics... and I wouldn't have taken this dive if you paid me to!

Nice job!

Ranjib · Jul 25, 2018

Superb !

Love the simplicity and frugalness of this project

. Thank you so much for sharing. I didn't know optical sensors are so cheap. I pay almost 12$ for each of those in amazon

Stella1979 · Jul 25, 2018

Thank you so much, everyone!

J is a bit of a quiet guy, but we both very much appreciate the kind words. We also greatly appreciate all we've been able to learn here and it feels great to contribute in a useful way.

SR52012 · Jul 25, 2018

Im confused by the float switches in the ATO container... but i am at work and will have to try to watch the video when i get a free sec.

redfishbluefish · Jul 25, 2018

Very nice DIY, and great job in detailing all the parts.

My only comment is that I've found these inexpensive float switches do not hold up when submerged. So what I've been doing is mounting them on the end cap of 1/2 inch CPVC by drilling and tapping that end cap. Use the little o-ring that comes with the float switch, and the top end of the float switch stays dry. Here are two recent examples.

The only reason CPVC was used is that it was thinner, less obtrusive, then regular PVC pipe.

Again, great write up....thanks for sharing.

Stella1979 · Jul 25, 2018

SR52012 said:
Im confused by the float switches in the ATO container... but i am at work and will have to try to watch the video when i get a free sec.

They are wired into the circuit and each of those float switches triggers a reminder or failsafe. The upper float switch, when triggered, will light the red LED that is visible on the control box, so this is a visual reminder that the reservoir is getting low. The lower float switch is only triggered when the reservoir is very low, and it will signal a loud auditory alarm and cut power to the ATO's pump, effectively shutting down the system until the reservoir is refilled.

redfishbluefish said:
Very nice DIY, and great job in detailing all the parts.

My only comment is that I've found these inexpensive float switches do not hold up when submerged. So what I've been doing is mounting them on the end cap of 1/2 inch CPVC by drilling and tapping that end cap. Use the little o-ring that comes with the float switch, and the top end of the float switch stays dry. Here are two recent examples.

The only reason CPVC was used is that it was thinner, less obtrusive, then regular PVC pipe.

Again, great write up....thanks for sharing.

Thank you SO much! We will certainly look into that.

This kind of thing is precisely why we have been so excited to share.

Comments, questions, and constructive criticism are all welcome here folks.

SR52012 · Jul 25, 2018

and im guessing the second optical it a "over fill" shut off correct?

redfishbluefish · Jul 25, 2018

If you do decide to use the pipe idea, every float switch I've purchased, the threads have been metric......M8 - 1.25. So you'll need a metric tap. I also don't have metric drill bits, but found the 17/64 bit works just fine to tap that hole.

Jguercio · Jul 26, 2018

SR52012 said:
and im guessing the second optical it a "over fill" shut off correct?

Yes. The second optical sensor, that points up, is a backup shut off and sounds the alarm.

Jguercio · Jul 26, 2018

redfishbluefish said:
If you do decide to use the pipe idea, every float switch I've purchased, the threads have been metric......M8 - 1.25. So you'll need a metric tap. I also don't have metric drill bits, but found the 17/64 bit works just fine to tap that hole.

Thank you very much for that info! Very helpful to know what's needed ahead of time!

Even Further · Jul 28, 2018

Seriously one of the best write ups I've ever seen. Crazy nice work here.

DirtDiggler2823 · Sep 24, 2018

Stella1979 said:
Hey there fellow reefers. So, I am not electrically inclined... at all. Luckily for me, the hubs is (we'll call him J). The following was written by him and I am very proud to share it here with you. This DIY ATO has been running successfully for a little over two weeks now, and while that is not a terribly long time, salinity has remained perfect and we are very happy with the build so far.

Please let us know what you think.

DIY Optical ATO

The StellATO

First off, I am self-taught, not an electrical engineer. I won't be held responsible for personal/pet/invert/coral harm or property damage. Now that we've got that out of the way, let's get into a little DIY electronics.

Well, after a year of looking at ATO's and considering a build, Stella put on this video to get in my head one day, and it worked! Gotta give credit where it's due, so thank you very much Reef Dudes @shiftline ... if I'm not mistaken.) Seriously, thanks dude.

Ultimately, we knew that we didn't want more equipment visible in our 20g long reef, but optical ATO's from trusted brands are expensive. Plus, there are always those bad reviews and disaster stories about these things failing. So, we wanted an option with as much redundancy as possible and for it to be easily and cheaply serviceable when needed.

This is not my first electronic build, but I would say that this is the most complicated circuit I've built so far.

This project requires soldering electronic components to a PCB(printed circuit board). Soldering irons and kits are pretty cheap and if you are inexperienced there are great videos on Youtube. Practice making simple circuits, like lighting an LED for example.

Anyhow, here we go.

Hardware
Project box(https://www.amazon.com/B0195UQJAU)$7.42
Optical sensors Qty: 2(https://www.ebay.com/itm/153034129330)$5.29 x 2
Mounts for sensors and float switches… diy’d these out of spare acrylic.
Float Switches Qty: 2(https://www.ebay.com/itm/112095617933)$1.14 x 2
Pump(https://www.amazon.com/B01IBKJWNG)$8.99
12V 2A power supply(wall wart)(https://www.amazon.com/B01GD4ZQRS)$7.69
12v Piezo Buzzer(https://www.taydaelectronics.com/buzzer-alarm)$0.56
Red LED(https://www.taydaelectronics.com/red led)$0.02
Connectors: 5.5 x 2.1mm Qty: 2 male, 2 female(https://www.ebay.com)$0.99

Aviation 3-pin Qty: 2 male, 2 female(https://www.ebay.com)$1.73 x 2
Aviation 2-pin Qty: 2 male, 2 female(https://www.ebay.com)$4.99

Circuit
Solderable half-size breadboard(https://ww.amazon.com/B072JXHQGL)$9.88
N-Channel Mosfets IRFZ44N Qty: 3(https://www.taydaelectronics.com/mosfet)$0.45 x3
5V Voltage Regulator 7805(https://www.taydaelectronics.com/lm7805)$0.23
555 timer IC (integrated circuit)(https://www.taydaelectronics.com/ic-555-timer)$0.13
Capacitors: 100uf 16v Qty: 1(https://www.taydaelectronics.com/capacitor)$0.02
.01uf 50v Qty: 1(https://www.taydaelectronics.com/capacitor)$0.03
Resistors: 470 ohm Qty: 3(https://www.taydaelectronics.com/resistors)$0.10
10K ohm Qty: 2(https://www.taydaelectronics.com/resistors)$0.10
220K ohm Qty: 1(https://www.taydaelectronics.com/resistors)$0.10
Diodes: 1N4004 Qty: 3(https://www.taydaelectronics.com/1n4004-diode)$0.02
1N4148 Qty: 1(https://www.taydaelectronics.com/1n4148-diode)$0.01
Relays: 12v SPDT Qty: 1(https://www.taydaelectronics.com/mini-relay-spdt-12vdc)$0.64
5v SPDT Qty: 1(https://www.taydaelectronics.com/mini-relay-spdt-5vdc)$0.62

Total: $60.21

Tools used
Drill
Step drill bit
Soldering iron, Solder, Flux
Wire stripping/crimping tool
Misc. hand tools - screwdriver, pliers, tweezers, etc.

Miscellaneous Materials
Wire - 22 AWG
Butt Connectors (20-24 AWG)
Electrical Tape
Adhesive - hot glue or double sided tape, for attaching the board inside the box.
Wire dressing - split loom, for example

Here’s what I did:

On one long side of the project box, I drilled appropriately sized holes with the step drill bit for the 4 male aviation connectors and installed them. On a short side, I drilled a hole for and installed one female barrel connector. On the other short side, I drilled for and installed another female barrel connector, the red LED which was hot glued in place, as well as a small hole for the buzzer’s speaker and glued it just inside on the inner wall of the box.

Soldered all electrical components to the breadboard, according to the schematic, leaving a few inches of wire hanging out as needed for the connectors, the LED, and the buzzer, (see breadboard image). Sorry guys, this is the fun/hard part that I just can’t list individual steps for.

3. Mounted the circuit board inside the project box using double-sided tape (3M command strips to be precise), or alternatively, a thick layer of hot glue could be used.

4. Soldered wires from the circuit board to the appropriate connectors, LED, and buzzer(according to the schematic and breadboard image) that were previously installed in the box. The single barrel connector on one short side of the box was used for power in, the 3-pin aviation connectors for the optical sensors, and the 2-pin aviation connectors were used for the reservoir’s float switches. The barrel connector on the side of the box with the led and buzzer goes to the pump. I labeled the box for 12v in, sensors 1 & 2, float switches 1 & 2, and pump.

5. Extended wires as needed for the pump and float switches. Attached a male barrel connector to the pump wires. Attached the 2-pin female aviation connectors to the float switch wires. Did not need to extend wires for optical sensors in our setup. Installed the 3-pin female aviation connectors on the optical sensors wires. Labeled all wires appropriately.

6. Made a holder out of acrylic and mounted the pump and float switches on it. For the upper float switch, the one that turns on the red led, I had to remove the clip and flip the float over in order to make it an NC (normally closed) switch. That way when the float goes down, the led turns on.

7. Attached a hose and put it all in the reservoir. Ran the hose to the tank and held it in place with a binder clip next to a powerhead.

8. Mounted the optical sensors in the tank on a piece of acrylic glued under the rim of the frame.

9. Mounted the box on the wall, ran wires, and plugged everything in. We dressed up the wires with split loom, zip ties, etc. (optional).

There is a delay in the circuit that waits until the sensor is not touching water for 24 continuous seconds in order to keep the pump from short cycling due to water movement. Then, water pumps until the first sensor touches water and stops. If the first sensor fails and does not stop the pump, the second sensor stops the pump when water touches it and sounds the buzzer. When the reservoir is low, the upper float switch triggers the red led on the control box to light up. When the reservoir is empty, the lower float switch will trigger and the pump will not run, so the system is disabled until the reservoir is refilled.