DIY optical ATO

[LarryD]

So I have been working for a bit on an osmolator style optical top off system using some parts I had laying around a tunze metering pump and this sensor ( I got it for about half what Amazon is selling it for now)

http://www.amazon.com/gp/product/B009NALEJE?psc=1&redirect=true&ref_=oh_aui_detailpage_o00_s01

For brains I have an arduino micro that I had laying around which is way over kill for this project but I might add on other functions later on.

I am in the testing phase right now and the only problem I have run into so far is that the sensor is sensitive enough that it gets into the gray area right at the actuation point that the slightest ripple will send it one way or the other. To help alleviate this I had built a slosh guard to still the water some but it was not able to get all of it.

I will try and keep anyone interested informed on problems that arise and once I get the design finalized I will post a B.O.M and some pictures.

[victoly]

program in a "debounce" function, where it has to reach a state and maintain the state for some period of time before the pump engages.

[LarryD]

program in a "debounce" function, where it has to reach a state and maintain the state for some period of time before the pump engages.

That is what I am currently working on, however building the prototype was simple programming it is a different story as programming has never been my strong suit.

[jestep]

Definitely interested to see how it turns out. That sensor is on the high end considering used osmolators are often in the $60 - $80 range. I've never been a huge fan of float sensors in SW though, especially when there's snails and other mobile stuff cruising around.

[LarryD]

Ya I actually got it for 30 bucks with free shipping, I guess they decided they could get more money for one. The thing was crazy simple to set up and it actually designed to work horizontally also and comes with an o ring so in theory you could thread it through the tank wall and have an extremely low profile ato system.

[jestep]

Ya I actually got it for 30 bucks with free shipping, I guess they decided they could get more money for one. The thing was crazy simple to set up and it actually designed to work horizontally also and comes with an o ring so in theory you could thread it through the tank wall and have an extremely low profile ato system.

That would be a huge benefit for pico or other tanks with minimal space. Just drill a hole and tap some threads in the wall and it would be the smallest ATO footprint by a long shot.

[LarryD]

To tap the wall would require an acrylic tank but you could put in like a 3/4in bulkhead and use a pvc plug that you have drilled and tapped for the probe. It is a little more intrusive than if you could just thread it into the wall but not bad. You could also on a thinner wall maybe get a nut on the inside to hold it but I would be wary of that as a potential leaking problem.

[LarryD]

So I have had to make the change over to a small mechanical relay for the pump because for some reason my transitors were not working (more proof that the little black boxes are nothing more than thinly veiled black magic). The program has been looked over by some people at the adafruit forums and they don't see any problems with it so it is back to testing.

[LarryD]

So mechanically the ato works wonderfully, the software is another story. About once a day the system freezes (always in the pump off position which I attribute equally to the way it is programmed and shear luck). I have some thoughts on how to fix the freezing problem but it will take me a bit of time to work up the new program. As always I will try and keep you guys in the loop.