DIY ATO w/backup & pump saver $30-50 Auto top off

[ajmckay]

Everyone should have an ATO. Seriously it's the best thing ever. An ATO functions to keep the salinity in your aquarium stable as water evaporates, but it also serves to eliminate daily topping off which can be difficult, especially if you take vacations. Commercially available units cost between $75 and $200. On the cheaper end though you usually only get one sensor - plus you still need to supply a pump, tubing, etc... While the units are nice I like to DIY stuff for cheaper and I don't really care how it looks because it's in my stand. My goal here was a truly automated solution with a backup sensor and a sensor in my ATO reservoir to prevent the pump from running dry. Also I wanted to use DC power to replace my old AC powered system for safety reasons and because my AC pump was loud cycling on and off.

 

Here's how I made my own ATO for about $40. Note that I already had some left over acrylic, AC adapter, and wire. I put the prices below one could reasonably expect to pay.

 

12v DC Pump $5-$20

5 pack of float switches $5-$10

Right angle float switch $3-$5

12v 4 pin Relay $3 - I used an automotive relay available at an auto parts store or online

12v AC Adapter with higher current than the pump + a little (20-30ma?) for the relay $0-$3

Vinyl tubing $0-$3

Wire $0-$2

Acrylic for the brackets $0-$5

Wire connectors (insulated) $0-$2

Zip ties $0-$1

Total: $30-$55

 

If you bought a cheaper DC pump, only bought the number of float switches you actually need, and if you already have some of the assembly components (wire, AC adapter, scraps of acrylic, etc...) this could be in the $30 range. I almost got this pump.

 

Assembly is pretty straight forward and so is functionality.

When the water level and the ATO reservoir are full the primary float is open (up = no power), the backup is closed (down = yes power) and the reservoir sensor is closed (down = yes power). The reservoir float switch is down because we have the sensor mounted upside down. The result is that the system is at rest.

 

Situation 1) If the water level in the sump/display drops then primary switch closes and power flows to the pump until the water level causes the primary switch to open again because the other 2 switches are also closed in this situation.

 

Situation 2) If the primary float switch gets stuck closed the pump will stay on. As the water rises it will cause the backup switch to open. This will cut off the power to the pump and now the backup switch is effectively the primary. Mark a line on the sump where the water level is normally so you can tell if you need to replace the primary float switch.

 

Situation 3) When the FW reservoir has water the float is closed. If the water is depleted enough to open the float switch the pump won't receive power even if the water level in the sump goes down. Of course you'll notice when that happens because your return pump will start to suck air. Having this extra switch prevents you from burning out your ATO pump.

 

I put the relay in a tupperware to keep it dry. The fuse holder is optional, not a bad idea though if you're able to size one correctly.

 

Here are the pics!

^ Whole system - used the wire connectors all over and zip ties so everything is in 1 bundle.

^ A little base I made so the pump stays upright and a mount for the float switch. Just some scrap acrylic.

^ Sump float switch and tubing holder. I can adjust the float switches up and down and secure the tubing from the reservoir. That's about it.

^ A closeup of the relay - some relays have 1,2,3,5 instead.

^ Finally here is what I'm replacing - Fortunately this single switch, AC spliced mash-up never electrocuted me or failed, but the pump was really loud switching on and off and the ATO reservoir for some reason always ran out of water in the middle of the night so the loud buzzing woke everyone up.

[dandelion]

I just finished my DIY ATO (well waiting for the pump... But circuitry is done). What I don't understand is why the two float switches in opposite directions. I simply have both switches at the same level with the same direction (or polarity... Or whatever you call that.) So if water level drops too low BOTH switches have to close before the pump will turn on. If somehow one got stuck on, the other one will (hopefully) turn off as water rises, thus killing the power. I'm going to put the pump on a timer as well so it only turns on like 2-3 times a day as a last resort redundancy.

 

Oh and instead of using neat looking acrylic, I just used 2 small pieces of egg crate connected at a right angle, and super glued a magnet on the vertical egg crate. I have ordered some neodymium magnets to put on the outside hopefully that will create a stronger hold.

[ajmckay]

I just finished my DIY ATO (well waiting for the pump... But circuitry is done). What I don't understand is why the two float switches in opposite directions. I simply have both switches at the same level with the same direction (or polarity... Or whatever you call that.) So if water level drops too low BOTH switches have to close before the pump will turn on. If somehow one got stuck on, the other one will (hopefully) turn off as water rises, thus killing the power. I'm going to put the pump on a timer as well so it only turns on like 2-3 times a day as a last resort redundancy.

 

Oh and instead of using neat looking acrylic, I just used 2 small pieces of egg crate connected at a right angle, and super glued a magnet on the vertical egg crate. I have ordered some neodymium magnets to put on the outside hopefully that will create a stronger hold.

 

Sounds cool - post a pic?

I'm not sure what you mean by the 2 floats in opposite directions... If you're talking about the switch in the reservoir being upside down that's simply because it's function is opposite of the in-sump switches. I want it to shut off the pump when the water level gets too low. When the reservoir is full the float is closed (it's floating up) and when the water level is low then it opens and shuts off the pump to prevent it from running dry.

 

For the in-sump float switches having them at the same level is fine, the only reason I had them at different heights is to keep one float out of the water such that if the one in the water gets mucked up the other one should be essentially clean.

[dandelion]

Here is my build

http://www.nano-reef.com/topic/366617-1122-diy-ato-dandelions-625-arc-build/?p=5185817

 

I misunderstood the reverse part. One thing I wasn't sure about putting in 2 level is what if salt creep got the upper switch stuck.... Then it'll lose its functionality. I prefer having both submerged and cleaning once a month.

 

Sounds cool - post a pic?

I'm not sure what you mean by the 2 floats in opposite directions... If you're talking about the switch in the reservoir being upside down that's simply because it's function is opposite of the in-sump switches. I want it to shut off the pump when the water level gets too low. When the reservoir is full the float is closed (it's floating up) and when the water level is low then it opens and shuts off the pump to prevent it from running dry.

 

For the in-sump float switches having them at the same level is fine, the only reason I had them at different heights is to keep one float out of the water such that if the one in the water gets mucked up the other one should be essentially clean.

[chappy6107]

how are you guys wiring the relay? I am unfamiliar with relays

[FishI]

how are you guys wiring the relay? I am unfamiliar with relays

So the relay has 4 prongs. Starting at the relay.

 

86: goes to each water level sensor. And then to the positive of the power supply.

 

85: goes to the negative of the power supply.

 

30: goes to the positive of the power supply

 

87: goes to the positive of the water pump.

 

*****this is how I am reading it from the diagram. I'd wait for someone who has built it to confirm. But it looks like it work in my mind.

 

 

Relays work with an electric magnet.

 

When the magnet gets power it pulls in the metal tab completes the circuit and the pump turns on. That's why you here them click. If you are really curious u can take them apart and look. Usually the top just snaps off.

[ajmckay]

Here is my build

http://www.nano-reef.com/topic/366617-1122-diy-ato-dandelions-625-arc-build/?p=5185817

 

I misunderstood the reverse part. One thing I wasn't sure about putting in 2 level is what if salt creep got the upper switch stuck.... Then it'll lose its functionality. I prefer having both submerged and cleaning once a month.

 

I think that either way should be fine. Note that I put wire connectors (insulated) near the float switches so I can take them out of the system easily. I don't anticipate significant corrosion or salt creep where they are, but a friend of mine suggested packing the connectors with grease - this would effectively prevent corrosion but could be a little messy. If you have poor ventilation or some water spray near the float switch connector then it might not be a bad idea. So far the past 2 weeks there's no creep or anything on the upper float switch - then again I have a few inches of wiggle room. If you're putting this in your display you may want the switches operating side by side to save space.

 

So the relay has 4 prongs. Starting at the relay.

 

86: goes to each water level sensor. And then to the positive of the power supply.

 

85: goes to the negative of the power supply.

 

30: goes to the positive of the power supply

 

87: goes to the positive of the water pump.

 

*****this is how I am reading it from the diagram. I'd wait for someone who has built it to confirm. But it looks like it work in my mind.

 

 

Relays work with an electric magnet.

 

When the magnet gets power it pulls in the metal tab completes the circuit and the pump turns on. That's why you here them click. If you are really curious u can take them apart and look. Usually the top just snaps off.

That should be correct - note that I used an automotive relay (because they're commonly available) and these numbers (30, 85, 86, 87) are commonly used in automotive - so if you know someone familiar with car electrical systems (you probably do) then they might even have some of these for you. Most of these I've seen are rated for 10-30 amps and draw very little current.

 

how are you guys wiring the relay? I am unfamiliar with relays

Haha I'm unfamiliar with relays as well - this is actually my first time using them in a project. So why am I writing this guide? Because they're actually very simple devices. I had a car friend explain them to me and it only took a few minutes. Plus he gave me one

 

You can also use relays to control AC power, but the wiring would be a little different and you would still need a 12v reference voltage as I understand it. I chose to use a DC pump here to increase the safety margin a little bit and because the DC pump I chose had the right flow rate. It's not aqualifter slow but it's not 200gph AC pump fast either. It's usually on for 30 seconds to a minute each time it cycles I believe and probably pumps in 300-500ml each time?

[chappy6107]

Thanks fellas. I probably need to grab one just to see it in person to better understand.

[gulfsurfer101]

This is a great thread man! Very informative and fail proof on all counts theoretically!

[ajmckay]

Hey thanks!

 

I really like the commercial ones, but I reef on a budget and thought if I could save $50 or so then I can spend that on more corals and stuff.

 

I use a 10g aquarium as a reservoir so I only have to replenish top off water about once per week.

[dandelion]

It's pretty straight forward. Like this relay, you will connect 2 and 7 through the 12V power adaptor and your float switches. When water level goes low, float switches will close and complete the circuit, activating the magnet. The magnet will then pull the switch originally connecting 8 and 5 to the other side, causing the switch to connect 8 and 6. So if you have your 120V power supply and 120V pump connected to 8 and 6 the pumps will work when the magnet is activated (which is when water level is too low).

 

 

Thanks fellas. I probably need to grab one just to see it in person to better understand.

[ajmckay]

sweet - thanks for the post. It's good to be able to wire up that style of relay.

[gulfsurfer101]

Hey thanks!

 

I really like the commercial ones, but I reef on a budget and thought if I could save $50 or so then I can spend that on more corals and stuff.

 

I use a 10g aquarium as a reservoir so I only have to replenish top off water about once per week.

I'll be running a 5.5 reservoir but I ran a water supply line directly to where the tank will be. That way I'm no longer hauling buckets of water around.

It's pretty straight forward. Like this relay, you will connect 2 and 7 through the 12V power adaptor and your float switches. When water level goes low, float switches will close and complete the circuit, activating the magnet. The magnet will then pull the switch originally connecting 8 and 5 to the other side, causing the switch to connect 8 and 6. So if you have your 120V power supply and 120V pump connected to 8 and 6 the pumps will work when the magnet is activated (which is when water level is too low).

 

 

This is the exact type of relay and harness I'll be using on my build. I'll splice into an extension cord rather than my pump and use a 12v adapter to supply the power.

[Jackal_Knight]

I'm just wondering why you would need a relay if your running everything off a 12v power supply? On ato system I build I used a relay because i didn't want to run 120v ac into my float switch so used 12v doc for that

[Rural]

what about digital sensors... float sensors are my issue, doesnt matter how many you have.

[ajmckay]

I'm just wondering why you would need a relay if your running everything off a 12v power supply? On ato system I build I used a relay because i didn't want to run 120v ac into my float switch so used 12v doc for that

 

So the issue for me at least was that the float switches were only rated to 1.0 amp (claimed) but the initial draw of my pump must spike slightly higher. So I burned out a float switch.

 

You might be able to get around this by buying a higher quality float switch but ultimately that was more expensive and would have taken longer than just running a relay - which as I understand it is going to be safer in the long run since there's very minimal power actually near the tank at that point.

[gulfsurfer101]

I just don't like the idea of running 120v in my tank! Phoo king scary stuff right there!

[chipmunkofdoom2]

I just don't like the idea of running 120v in my tank! Phoo king scary stuff right there!

 

+1. This is why I went with a cheap 12v peristaltic pump off Ebay for my DIY ATO. Cost about $10. I tested this pump, at max it pulls about 150mA , which means the whole system uses 1.8W @ 12VDC, or about 0.75W on the 5V phone charger I'm using as a power supply. In addition to the benefits afforded to you by using a peristaltic pump, since this thing is so low power, no relay is required. Simply run the power supply to the pump and splice as many float switches as you want into the circuit.

[Horerczy]

This diy gave me neat ideas for a diy chiller pump and DC return pump.

 

Also the ato is really nice example of the K.I.S.S. system. Might need to make one of those.

[ajmckay]

what about digital sensors... float sensors are my issue, doesnt matter how many you have.

I think it should work for any sensor type as long as you account for whether it's a normally open or normally closed switch and it has similar electrical characteristics.

 

 

+1. This is why I went with a cheap 12v peristaltic pump off Ebay for my DIY ATO. Cost about $10. I tested this pump, at max it pulls about 150mA , which means the whole system uses 1.8W @ 12VDC, or about 0.75W on the 5V phone charger I'm using as a power supply. In addition to the benefits afforded to you by using a peristaltic pump, since this thing is so low power, no relay is required. Simply run the power supply to the pump and splice as many float switches as you want into the circuit.

Good point - to get around a possible start-up voltage spike going through the switch you could just use a lower power pump.

 

The pump I chose utilizes about 1A and the max limit on the float switch I think was 1A but I'm guessing it's actually lower, or the initial draw is higher than 1A.

 

I thought about using a peristaltic pump but I have a 70 gallon system, so I thought that might be on the slow side for a system my size. For a smaller tank I think a peristaltic pump would be ideal. Mind posting a pic/link to the pump you used? I'll see if I can find my thread from a while ago asking for pump suggestions as well.

[chipmunkofdoom2]

This is the one I used:

 

http://www.ebay.com/itm/DC-12V-D4-Lab-Dosing-Pump-Peristaltic-Head-Chemical-Water-Liquid-Analysis-/121641165745?hash=item1c5260e3b1:g:VOcAAOSwPhdVR0uA

 

About $9.40 USD shipped. Comes from China, so it takes a week or two, but it goes by quickly. The pump is rated for up to 100ml/min, and at just over 12VDC it's almost spot on. I clocked this thing at about 1.5GPH. On my phone charger that I used because I didn't want to buy another power supply, it does about 0.5GPH, but that's still way more than enough for my tank.

 

I was concerned about using a peristaltic pump because of flow rate as well, but there are several on Ebay that cite max flow rates around 100ml/min (about 1.5GPH). About how much topoff water do you use per day? 1.5GPH might work for you. The good thing about a peristaltic pump is that it doesn't get damaged if it runs dry, you don't have to worry about back siphoning, and the pumping height is amazing. I only had about 9 feet to test it with, but I noticed zero drop in flow, even at 9'.

[dandelion]

I'll certainly look into that. My build for my Pico used a Tom Aqualifter. I can't use the same pump for my sumpless 29G because it is too high. Plus without having to wire a relay it will be so much easier.

 

This is the one I used:

 

http://www.ebay.com/itm/DC-12V-D4-Lab-Dosing-Pump-Peristaltic-Head-Chemical-Water-Liquid-Analysis-/121641165745?hash=item1c5260e3b1:g:VOcAAOSwPhdVR0uA

 

About $9.40 USD shipped. Comes from China, so it takes a week or two, but it goes by quickly. The pump is rated for up to 100ml/min, and at just over 12VDC it's almost spot on. I clocked this thing at about 1.5GPH. On my phone charger that I used because I didn't want to buy another power supply, it does about 0.5GPH, but that's still way more than enough for my tank.

 

I was concerned about using a peristaltic pump because of flow rate as well, but there are several on Ebay that cite max flow rates around 100ml/min (about 1.5GPH). About how much topoff water do you use per day? 1.5GPH might work for you. The good thing about a peristaltic pump is that it doesn't get damaged if it runs dry, you don't have to worry about back siphoning, and the pumping height is amazing. I only had about 9 feet to test it with, but I noticed zero drop in flow, even at 9'.

[NewbReefer316]

Thanks for the write up. I'm looking into making a couple ATO's for some different tanks. I'm definitely interested in a couple with the peristaltic pumps since it'll be used on smaller tanks and possibly look into some of the optical sensors for the brackish tank in our living room.

[dandelion]

Share on here if you figure out how to do an optical sensor! I would love to know how!

 

 

Thanks for the write up. I'm looking into making a couple ATO's for some different tanks. I'm definitely interested in a couple with the peristaltic pumps since it'll be used on smaller tanks and possibly look into some of the optical sensors for the brackish tank in our living room.