Smitty's Pico Ato Guide.

[SmittyCoco]

I know there are a few threads about this, but this is mine Per request (SeaMonkeyz13).

 

I have been running a picotope for 18+ months. I have had my ups and downs,but one thing that has been rock solid is my diy ato. I built it a little over a year ago. So with the introduction out of the way here it goes.

 

I wanted something cheap and reliable. I had read several threads about diy atos and this is what I came up with.

 

I used a simple aqualifter($12.99 lfs) with a prefilter (1.99 lfs).

 

 

I used a 2 gallon bucket found at Osh (Orchard Supply Hardware). It was 1.99 and .99 for the lid. The water supply lasts me 2 weeks +. I also Have a sunpod 70 over my pico. As you can see in the pic . I drilled two holes in the lid. One for ventilation. The other to draw water from. I used 2 rubber grommets(.39) found in the loose hardware section. And 2 plastic nipples(.69) 1 to attach the hose the other is just the vent.

 

 

The inside consists of a 1 inch piece of the vinyl tubing attached to the nipple. And a rigid line inside that. Make sure the ridgid tube goes ALL the way to the bottom. Make full use of the bucket !

 

 

I simply took an extesion cord( $1.00 from the dollar store ) and cut one side to sauter the float switch in. I put electrical wire shrinkers over the wires before the sautering took place. Instead of electrical tape I just shrunk it over the exposed sautered wires to protect the area.

 

 

As for My Float switch I ordered from Chicago sensor. Thanks for the tip Aaron (elFabuloso). For a snail gaurd I cut a tube in half of aquamend. I drilleded holes in the bottom sides . And 2 in the lid. One to fit the float switch and one to vent the chamber. I have collected a ton of plastic clips from various displays at your local walmart and such. I know someone who works there. Not stolen !

 

 

 

As you can see the Float switch is simply attached to the clip using a lfs rubberband. Finally a use for those things ! This makes for adjustment of the water level a breeze. My original plan was to set the level I wanted and super glue it in place. After awhile I just thought it was easier to keep the rubberbands in use for adjustment if needed. I change out the rubberband every couple weeks or so. It is Very important to keep an eye on this. After 2-3 weeks they need to be replaced.

 

And installed

 

 

 

I hope this is usefull to anyone needing ideas for thier own diy ato. If you have an Questions ask away. I would estimate my total to build the entire set up was 20-25$ . Depends on what you have on hand. It could be cheaper if you have some of the pieces. This is intended to be a guide and not a definite. Another note . I was very paranoid about not having an inline relay. That is an option . Or can be hooked up to a controler for , well, control. In the year I have had this in use. I have never had an issue. ( knock on wood )

 

 

And here is a fts of my little pico

 

 

Enjoy ! And happy Reefing !

[sae647]

beautiful tank!

 

good work on the ATO.i'm sure more people will comment about this, but it seems to be the general consensus that all float switch setups should use a relay so the float switch does not handle line voltage. I recently built a system with a relay and it was VERY easy to wire up in a project box.

[Cheetos]

How much does your water level drop in the tank before the float drops enough to kick on the aqualifter?

[SmittyCoco]

How much does your water level drop in the tank before the float drops enough to kick on the aqualifter?

 

Maybe an 1/8' of an inch. The water level is very stable.

[neanderthalman]

No, it's not ok to run that large of an inductive load through a reed switch. It never is, period. It's not the operating current, but the inrush current on start that is the problem. Not only that, you've failed to provide any suppression, so your contacts take further beating when the switch attempts to break the circuit.

 

I guarantee that you will weld the switch contacts and your ATO will be stuck on, flooding your tank with RO. The only question is when. Especially if you put the switch in a turbulent environment.

 

Not only that, but your design completely fails to include a redundant switch or timer, despite the well-known failure issues with single-floatswitch ATOs from algae fouling and snailriding.

 

However, I do like your use of PVC for the floatswitch hanger. Creative.

 

Edit - you should know that this is meant to help you, not shoot you down. Your design has flaws, but they can be easily fixed with a relay and a second floatswitch.

 

You've eliminated snailriding. That's about it.

 

To help you avoid catastrophe, and since you are dealing with a small space, the RC timer on this particular design will let you run safely with a single floatswitch. The second "barebones" kit was cut out of the quote for brevity.

 

As promised - DIY designs using a relay. There are two - one is a higher cost "cadillac", which includes multiple levels of redundancy and an on-board DC power supply. The second is a basic "barebones" kit.

 

I've made some upgrades to the design. It now includes overcurrent protection, a voltage regulator, as well as a simple RC timer. This adds an additional layer of redundancy. The relay will shut off after an adjustable time delay, or if the backup floatswitch is lifted. It also removes the absolute requirement to have a backup floatswitch, should you so desire - simply short the backup floatswitch terminals with a jumper. I would not personally run it this way, but this may be of benefit in very small tanks where a second float will not fit.

 

On to the good stuff:

 

 

You'll need the following:

 

PCB - $17.46

Rectifier - $0.51

3300uF Capacitor - $0.82

Transformer - $3.15

Relay - $2.58

Diode - $0.27

Fuse Holder X2 - $0.61 ea

1A Fuse - $0.32

1M Potentiometer - $0.83

0.1uF Capacitor - $0.18

10uF Capacitor - $0.16

Terminal Strip - $1.26

MOSFET - $0.68

12V Regulator - $0.54

100mA Fuse - $1.34

10k Resistor - $0.15

 

Total Cost - $31.32. The truly frugal could cut the cost in half by duplicating the circuit on a perforated board, if they felt up to the task.

 

For the floatswitches, you may use whatever you like, so long as it is "normally closed". This means that when the water level drops, the switch turns "on". I personally use the FLT015 from Chicago sensor - this is the floatswitch from the now defunct www.floatswitches.net, which used to be the goto place for DIY ATO's. It was sad to see them go, but at least the switches are still available to us. The cost on the switches is $7.00 each. For the price, I'd pick up an extra to keep on hand in case you have a failure.

 

 

For my fellow Canadians - I know that some of the above listed parts are not listed as in-stock items on the Canadian version of Digikey. I am putting together a separate list and will post it here as soon as it is complete.

 

[SeaMonkeyz13]

I know there are a few threads about this, but this is mine Per request (SeaMonkeyz13).

 

I have been running a picotope for 18+ months. I have had my ups and downs,but one thing that has been rock solid is my diy ato. I built it a little over a year ago. So with the introduction out of the way here it goes.

 

I wanted something cheap and reliable. I had read several threads about diy atos and this is what I came up with.

 

I used a simple aqualifter($12.99 lfs) with a prefilter (1.99 lfs).

 

 

I used a 2 gallon bucket found at Osh (Orchard Supply Hardware). It was 1.99 and .99 for the lid. The water supply lasts me 2 weeks +. I also Have a sunpod 70 over my pico. As you can see in the pic . I drilled two holes in the lid. One for ventilation. The other to draw water from. I used 2 rubber grommets(.39) found in the loose hardware section. And 2 plastic nipples(.69) 1 to attach the hose the other is just the vent.

 

 

The inside consists of a 1 inch piece of the vinyl tubing attached to the nipple. And a rigid line inside that. Make sure the ridgid tube goes ALL the way to the bottom. Make full use of the bucket !

 

 

I simply took an extesion cord( $1.00 from the dollar store ) and cut one side to sauter the float switch in. I put electrical wire shrinkers over the wires before the sautering took place. Instead of electrical tape I just shrunk it over the exposed sautered wires to protect the area.

 

 

As for My Float switch I ordered from Chicago sensor. Thanks for the tip Aaron (elFabuloso). For a snail gaurd I cut a tube in half of aquamend. I drilleded holes in the bottom sides . And 2 in the lid. One to fit the float switch and one to vent the chamber. I have collected a ton of plastic clips from various displays at your local walmart and such. I know someone who works there. Not stolen !

 

 

 

As you can see the Float switch is simply attached to the clip using a lfs rubberband. Finally a use for those things ! This makes for adjustment of the water level a breeze. My original plan was to set the level I wanted and super glue it in place. After awhile I just thought it was easier to keep the rubberbands in use for adjustment if needed. I change out the rubberband every couple weeks or so. It is Very important to keep an eye on this. After 2-3 weeks they need to be replaced.

 

And installed

 

 

 

I hope this is usefull to anyone needing ideas for thier own diy ato. If you have an Questions ask away. I would estimate my total to build the entire set up was 20-25$ . Depends on what you have on hand. It could be cheaper if you have some of the pieces. This is intended to be a guide and not a definite. Another note . I was very paranoid about not having an inline relay. That is an option . Or can be hooked up to a controler for , well, control. In the year I have had this in use. I have never had an issue. ( knock on wood )

 

 

And here is a fts of my little pico

 

 

Enjoy ! And happy Reefing !

 

Thank SmittyCoco your Awesome!!! Thanks for taking your time to making this ATO thread I requested

Now i need to make magic! BTW ur Picotope is amazing calm is beautiful!

 

+++++

 

 

 

SeaMonkeyz13

[AdrianBryce]

I may be missing something, but can you tell (in detail) me how you have the float switch connected to the pump?

[neanderthalman]

I may be missing something, but can you tell (in detail) me how you have the float switch connected to the pump?

 

How? Short answer - it's connected wrong.

 

Long answer, see my earlier post. Use a relay, reed (float) switches are not intended for switching inductive loads and will fail over time.

[coolwaters]

that tank looks very crowded.

[C.ton9187]

How? Short answer - it's connected wrong.

 

Long answer, see my earlier post. Use a relay, reed (float) switches are not intended for switching inductive loads and will fail over time.

 

I couldn't agree more, get the relay and the shutoff floatvalve on there!! this is a heartbreaker waiting to happen. disconnected this ato before you come home to a reef full of r/o water and that won't be hard to do with that tank size, just a warning man, nothing personal.

[acropora1981]

I have an improvement for you unrelated to the relay; use a plastic 'zip' tie, instead of an elastic band. They last for years. If you need to clean it, you can just cut off the wire tie and zip on a new one after its fixed. It will be more secure that way.

[lovelandbmxrider]

well i found my project for the next week THANKS!!!

[gregzbobo]

I have an improvement for you unrelated to the relay; use a black plastic 'zip' tie, instead of an elastic band. They last for years. If you need to clean it, you can just cut off the wire tie and zip on a new one after its fixed. It will be more secure that way.

 

fixed to reflect black being much more UV resistant than white zip-ties.

[SmittyCoco]

I just used a lfs rubberband for ease. And most everyone has them. As for the relay? I would like to incorporate one. I can't make heads or tails of that diagram though. It has worked for over a year so maybe over time ? Anyways gl . Happy reefing.

[neanderthalman]

As for the relay? I would like to incorporate one. I can't make heads or tails of that diagram though. It has worked for over a year so maybe over time ?

 

Yes, the issue is wear and tear over time. The arcing and sparking from driving the load directly eventually damages the tiny, almost hair-like contacts inside the floatswitch.

 

It is possible to drive a load directly if the load is small enough. Most of the pumps used for ATOs, compared with the rating of the switches (120V 0.5A), are not suitable - even though the pumps draw less than 0.5A. The issues have to do with establishing and collapse of the magnetic field that drives the pump motor. All electric motors experience a phenomenon called inrush, which is a brief period during startup (establishing field) where the current draw of the motor can be anywhere from about six to ten times the normal operating current. By this estimate, a 0.5A floatswitch can only operate a pump that draws 0.05A.

 

The second point is that when you open the switch to shut off the pump, the magnetic field of the pump now acts as a generator of sorts as it collapses. If the pump was drawing 0.05A at 120V during operation, and you open the switch, the magnetic field of the pump will "force" current to continue to flow, ramping down relatively slowly from 0.05A. You cannot have a sudden change in current (discontinuity) when dealing with an electric motor because of the magnetic field. In order for the pump to have 0.05A of current flowing in the instant after the switch opens, it will produce whatever voltage is necessary to spark across the contact gap - whether thats 1000V, 10000V, whatever (within other limits, but we don't need to go there), but it will exceed the rating of the switch and damage it.

 

I know that design is fairly complex, but there's good reason. It included the power supply and a backup timer for three levels of redundancy. If all you want is a relay, I also have this much simpler design:

 

You also don't need to make heads nor tails of it (nor the v1.3). It's a printed board that you can purchase for a few bucks from batchPCB. All you have to do is mount the components and laugh maniacally that "it's alive".

 

I have also put together a barebones kit. This is a lower cost ATO that does not include the features of the V1.3. It requires an external 12V power supply, and does not include the RC timer. It does, however, still have a connection for a backup floatswitch.

 

 

 

Parts List:

 

PCB - $10

Relay - $2.58

Diode - $0.27

Fuse Holder - $0.61

1A Fuse - $0.32

Terminal Strip - $1.26

 

Total Cost - $15.04

 

You could also save the ten bucks on the PCB and duplicate this on a perforated board with minimal effort.

 

As with the V1.3, any normally closed (on when down) floatswitch can be used. I personally use and recommend the Chicago Sensor FLT015 - $7.00.

[c_k_kuehne]

I agree about the relay but.........

 

seems that particular float is made for full line voltage. Here is the specs taken from the link OP supplied.

 

Specifications:*

Temperature: -10 ~ +80°C

Contact rating: 50W

Max Switching Voltage: <=220VAC

Min Breakdown Voltage: 600VDC

Max Switching Current: 2.5A

Max Contact Resistance: 100mΩ

 

With specs like that seems the intended use for that float switch is full line voltage -- am I wrong ??

[acropora1981]

I just used a lfs rubberband for ease. And most everyone has them. As for the relay? I would like to incorporate one. I can't make heads or tails of that diagram though. It has worked for over a year so maybe over time ? Anyways gl . Happy reefing.

 

Zip ties you can get at every hardware store, and even just about every dollar store I've ever been in. And they will never break.

 

If you've never used them in a DIY project man you are missing out! I use them all the time to secure lots of different things.

[neanderthalman]

I agree about the relay but.........

 

seems that particular float is made for full line voltage. Here is the specs taken from the link OP supplied.

 

Specifications:*

Temperature: -10 ~ +80°C

Contact rating: 50W

Max Switching Voltage: <=220VAC

Min Breakdown Voltage: 600VDC

Max Switching Current: 2.5A

Max Contact Resistance: 100mΩ

 

With specs like that seems the intended use for that float switch is full line voltage -- am I wrong ??

 

Yes, but it's not your fault. Electricity can be tricky stuff, and if you don't know it inside and out, it's easy to miss a key detail.

 

The problem is not that it carries full line voltage. If pumps were a resistive load, then no problem. Pumps are an inductive load, which introduces damaging transient effects that are only encountered on startup and shutdown. This is what I described earlier.

 

With regards to this specific switch, it should be pointed out that the switch is not as robust as the specifications would have you believe. Sure, it can switch 220VAC, and it can switch up to 2.5A. Sounds good right? However, it cannot switch both at the same time. This is where the 50W contact rating comes in.

 

At a nominal voltage of 120V, that means you can only switch up to about 0.4A - not 2.5A. You could switch 2.5A at 20V and below. Above 20V, you have to derate the current rating of the contacts, because you have sufficient voltage to arc during operation. Reading datasheets is not always easy, and missing something like the 50W contact rating is very common indeed.

 

Also note that the specifications on datasheets are based on resistive loads (unless indicated). Again, pumps are inductive loads, which require further derating of the switch. As I already mentioned, a pump on startup can produce up to ten times the normal operating current. Thus, this switch can really only safely operate a pump up to 5W. Now, an MJ400, for example, is only 5W so you're just squeaking by here as doable. The aqualifter is 3W, which is definitely doable - for startup.

 

Which leads to the second problem, which is the lack of suppression on pump shutdown. The pump will act as a voltage source in order to maintain a continuous current flow. Considering the breakdown voltage of the switch is only 600VDC, or about three times the peak of a 120V AC waveform, the pump will most definitely generate sufficient voltage to arc and wear out the contacts on contact opening. It will briefly generate thousands of volts if it has to - this is a fundamental rule to how inductive loads behave.

 

This is what will eventually damage the switch.

[bulldogpet]

What is the purpose of the prefilter? Who carries it other than LFS ?

[SmittyCoco]

What is the purpose of the prefilter? Who carries it other than LFS ?

Pump protection redundency. For a $1.99 I thought it was worth it for whatever reason. Apparently my switch setup could use the same foresight ?

[rickjg]

Yes, but it's not your fault. Electricity can be tricky stuff, and if you don't know it inside and out, it's easy to miss a key detail.

The problem is not that it carries full line voltage. If pumps were a resistive load, then no problem. Pumps are an inductive load, which introduces damaging transient effects that are only encountered on startup and shutdown. This is what I described earlier.

With regards to this specific switch, it should be pointed out that the switch is not as robust as the specifications would have you believe. Sure, it can switch 220VAC, and it can switch up to 2.5A. Sounds good right? However, it cannot switch both at the same time. This is where the 50W contact rating comes in.

neanderthalman,

 

Would running a low voltage (battery powered) air pump solve the problem encountered on startup and shutdown?

http://www.marinedepot.com/Hagen_Battery_O...-FIARBO-vi.html

If you were to wire in 5V/550mA phone charger to replace the air pump batteries would that make any difference with the switch? That's assuming the air pump can handle the extra power.

 

Thanks

Rick

[neanderthalman]

neanderthalman,

 

Would running a low voltage (battery powered) air pump solve the problem encountered on startup and shutdown?

http://www.marinedepot.com/Hagen_Battery_O...-FIARBO-vi.html

If you were to wire in 5V/550mA phone charger to replace the air pump batteries would that make any difference with the switch? That's assuming the air pump can handle the extra power.

 

Thanks

Rick

 

You should not have a problem, no. When the voltage is low, then you no longer have sufficient "oomph" to create the damaging spark on startup. In addition, the likelihood of the pump generating a kickback greater than 600V on shutdown is fairly low. Regardless, for the cost of a simple ten cent diode, you can put a basic DC suppression circuit in place. What you do is put the diode in parallel with the pump, with the white stripe end connected to the positive (red) wire. This provides an alternate path for the current generated by the pump, essentially short circuiting the damaging kickback.

 

I am not certain that your cell phone charger is suitable for the pump, it's going to have almost double the normal operating voltage of the pump. It will probably not directly damage the pump, but the extra voltage will cause the current to increase as well. This means the pump will run hotter and if it cannot exhaust the extra heat, you could eventually burn up the pump.

 

What you have in your favor is that the pump will not be running continuously. This means that the pump will have extra time to dissipate the heat between fillups. However, this does mean that if your reservoir becomes empty, then the pump will run continuously and you are likely to ruin it. You can use a second floatswitch to shut off the pump if the reservoir is empty. That should prevent this occurrence.

[SmittyCoco]

Coming up on two years with this ato and still a success. Hope to have helped others with this design.

[EvMiBo]

Smitty. I think it would be fine, but to conceal the float switch and tubing do you think it's okay to put it in something like this ?

[rO.oster]

hows that float switch doing?