ctenophore November 6, 2010 Share November 6, 2010 Hi All! Our pressure-sensing level switch used in our Davy Jones Skimmate Locker has a great dual role: auto top-off controller! It's magnet-mounted, so installation anywhere in your sump is a snap (literally; watch your fingers as the magnet will hold through 3/4" glass!) Snails can't crawl on it and cause a false signal, and calcium can't build up on it and cause it to stick like magnetic floats. No moving parts means less chance of failure. Special deal: Order with either a K1 or K2 Kalk Stirrer and save $10! Link to comment Share on other sites More sharing options...
quazi November 11, 2010 Share November 11, 2010 Very cool. Can I order the ATO without the full locker? Link to comment Share on other sites More sharing options...
quazi November 11, 2010 Share November 11, 2010 Very cool. Can I order the ATO without the full locker? Never mind, I found it on the site. Good deal!! Link to comment Share on other sites More sharing options...
ctenophore November 12, 2010 Author Share November 12, 2010 Never mind, I found it on the site. Good deal!! Whoops! I guess a link to it in the first post might have helped Link to comment Share on other sites More sharing options...
Origami November 12, 2010 Share November 12, 2010 Nicely integrated package, guys. I really like the magnet mount idea. This is perfect for those little nano's with their tightly integrated sumps in back. Is there any hysteresis in the differential pressure switch to keep it out of a bang-bang (rapid toggling between on and off) situation? Link to comment Share on other sites More sharing options...
Chad November 12, 2010 Share November 12, 2010 Justin, hope you dont mind me answering. Tom, no, these pressure switches are awesome. The part that goes in the tank is basically just an air tube (nothing that would be affected by the magnet). As soon as water rises to the level of the tube, the pressure insude the tube begins to rise and trips the switch. The electrical portion of the differential pressure switch is mounted in the relay box. No electrical wires near water or the magnet. Link to comment Share on other sites More sharing options...
Larry Grenier November 12, 2010 Share November 12, 2010 Nicely integrated package, guys. I really like the magnet mount idea. This is perfect for those little nano's with their tightly integrated sumps in back. Is there any hysteresis in the differential pressure switch to keep it out of a bang-bang (rapid toggling between on and off) situation? Says this on the web-page ...and features a built-in range buffer to prevent hysteresis, or rapid on-off switching that sometimes occurs... sounds cool. Mine clicks on-&-off-&-on-&-off... because of movement in the sump. Link to comment Share on other sites More sharing options...
Origami November 12, 2010 Share November 12, 2010 Justin, you may want to correct that "prevent hysteresis" (if, as Larry has shown, this is what it says on the website) as that is exactly what you want. Hysteresis is what prevents the "on-off" switching. It's what was present in the old 7414 inverters - it's a positive feedback loop that helps to drive the response away from the balance point. I'm familiar with these differential pressure switches. I'm just wondering if you're able to quantify the hysteresis. Since it's sensitive to a 1/2" WC pressure, I can't imagine that it would be much. Also, now that I'm thinking about it, is there an internal option to rewire it to be normally open (NO) rather than normally closed (NC)? Link to comment Share on other sites More sharing options...
Chad November 12, 2010 Share November 12, 2010 Also, now that I'm thinking about it, is there an internal option to rewire it to be normally open (NO) rather than normally closed (NC)? A question that I have as well. (Or can it be used as a low level switch?) Link to comment Share on other sites More sharing options...
ctenophore November 13, 2010 Author Share November 13, 2010 Justin, you may want to correct that "prevent hysteresis" (if, as Larry has shown, this is what it says on the website) as that is exactly what you want. Hysteresis is what prevents the "on-off" switching. It's what was present in the old 7414 inverters - it's a positive feedback loop that helps to drive the response away from the balance point. I'm familiar with these differential pressure switches. I'm just wondering if you're able to quantify the hysteresis. Since it's sensitive to a 1/2" WC pressure, I can't imagine that it would be much. Also, now that I'm thinking about it, is there an internal option to rewire it to be normally open (NO) rather than normally closed (NC)? Whoops, good catch Tom. Thanks I will update the site. Re: quantification, do you mean distance or lag time? units? Our original prototypes had a NC/NO switch but we removed it to make wiring simpler and keep cost down. As I mentioned to Chad, we can wire up some NO ones easily enough. Link to comment Share on other sites More sharing options...
dandy7200 November 13, 2010 Share November 13, 2010 Justin, you may want to correct that "prevent hysteresis" (if, as Larry has shown, this is what it says on the website) as that is exactly what you want. Hysteresis is what prevents the "on-off" switching. It's what was present in the old 7414 inverters - it's a positive feedback loop that helps to drive the response away from the balance point. I'm familiar with these differential pressure switches. I'm just wondering if you're able to quantify the hysteresis. Since it's sensitive to a 1/2" WC pressure, I can't imagine that it would be much. Also, now that I'm thinking about it, is there an internal option to rewire it to be normally open (NO) rather than normally closed (NC)? Tom, The switch has an internal regulated hysteresis of 50% of the set point. The set point is .1psi so the reset is approx .05psi This prevents the rapid on/off cycles, although since the switch is rated for 10,000,000+ cycles it would be of little concern if there was a bit of cycling. The switch can be wired for NO rather than NC as Justin mentioned, but we are also planning a digital out version that can hook into aquarium controllers that will be able to use the more advanced logic those devices are capable of so we are trying to get that product to market first and see if there is still interest in the NO hardwired version. Dan Link to comment Share on other sites More sharing options...
beatle March 6, 2011 Share March 6, 2011 Bump for a question on attaching the switch to a controller (I have an AC3). Do you need to buy the breakout box for the AC3 or does this simply plug into the controller? I have an Osmolator which works great, but it requires another $60 option if I want to use a peristaltic pump with it to pump topoff from my basement. It also has no way to send me alarms via email if something goes wrong. As far as reliability goes, have you noticed any issues with salt creep around the opening affecting reliability? I'm guessing for something that goes in and out of the water, this would be a problem, but it seems like reliability is one of the chief benefits of this switch in that it's not affected by coraline or salt creep. Link to comment Share on other sites More sharing options...
Jon Lazar March 6, 2011 Share March 6, 2011 Couldn't you also adjust the diameter of the sensor to change how sensitive the entire unit is to water level changes? A larger tube would trip the pressure switch with just a small change in water level, but a smaller tube would require a larger change in water level. (Or maybe I have it backwards? Hydraulics makes my head hurt.) Link to comment Share on other sites More sharing options...
Chad March 6, 2011 Share March 6, 2011 No, John, you have the physics right... yes, a larger tube should make the level variation smaller. With the increased sensitivity, I would think the number of undesired cycles would go up to, though. Link to comment Share on other sites More sharing options...
Jon Lazar March 6, 2011 Share March 6, 2011 No, John, you have the physics right... yes, a larger tube should make the level variation smaller. With the increased sensitivity, I would think the number of undesired cycles would go up to, though. Right; so you use a smaller tube if you want fewer cycles. Link to comment Share on other sites More sharing options...
ctenophore March 8, 2011 Author Share March 8, 2011 Bump for a question on attaching the switch to a controller (I have an AC3). Do you need to buy the breakout box for the AC3 or does this simply plug into the controller? I have an Osmolator which works great, but it requires another $60 option if I want to use a peristaltic pump with it to pump topoff from my basement. It also has no way to send me alarms via email if something goes wrong. As far as reliability goes, have you noticed any issues with salt creep around the opening affecting reliability? I'm guessing for something that goes in and out of the water, this would be a problem, but it seems like reliability is one of the chief benefits of this switch in that it's not affected by coraline or salt creep. The breakout box is not mandatory but it makes the setup much easier. Our digital out version just ships with a pair of bare wires for this purpose- plug them into a breakout box (or equavalent input connector on other controllers) and you're done. Otherwise, you can solder an appropriate plug on the end; the pinout diagram is listed in the neptune manual. It is not tricky to do, but you have to find a minidin-8 plug (I believe that is the plug format), likely from digikey.com. Salt creep doesn't affect the sensor at all IME. No, John, you have the physics right... yes, a larger tube should make the level variation smaller. With the increased sensitivity, I would think the number of undesired cycles would go up to, though. I don't think this is right for two reasons. 1) pressure doesn't change based on diameter of container. e.g., a tube 1/8" diameter x 30 feet high full of water has the same pressure at the bottom as a tube 6' diameter x 30' high. The same principal applies in reverse, when a vessel of air is pushed underwater. 2) we tried varying tube diameters and saw no difference, so empirical evidence supports #1. But I'd be happy if I am wrong, as it would be really easy to adjust sensitivity of the ATO! Link to comment Share on other sites More sharing options...
Mando77 March 8, 2011 Share March 8, 2011 This works great with apex and will save you some money if you are looking at the tunze ato Link to comment Share on other sites More sharing options...
Chad March 8, 2011 Share March 8, 2011 I don't think this is right for two reasons. 1) pressure doesn't change based on diameter of container. e.g., a tube 1/8" diameter x 30 feet high full of water has the same pressure at the bottom as a tube 6' diameter x 30' high. The same principal applies in reverse, when a vessel of air is pushed underwater. 2) we tried varying tube diameters and saw no difference, so empirical evidence supports #1. But I'd be happy if I am wrong, as it would be really easy to adjust sensitivity of the ATO! Yes, that is true, but the pressure is not being generated by the weight of the fluid, it is generated by changing the volume of a fixed amount of gas in the tube (i.e., the gas is being compressed). It is a PV/T relationship, not Pascal's law. To prove this to myself, I did some math... [insert 20 minutes of playing with an excel doc here]... ...and found out that my thinking earlier was wrong! It seems that the cross section of the tube ends up being factored out of the equation altogether. In this case p1v1/t1 = p2v2/t2, temperature cancels out since it is the same. Then inserting, substituting the equation for volume, and cancelling out stuff that is the same on both sides (diameter and pi) and you end up with p1h1 = p2h2 (where h1 is the length of the tube and h2 = h1-level change), so diameter doesn't matter at all. I feel schooled! Thank you for setting me straight and reminding me once again that I should just look at the math up front since just thinking about it is not always intuitive! Link to comment Share on other sites More sharing options...
FearTheTerps March 23, 2011 Share March 23, 2011 Any idea when you guys will have the outlet version back in stock? Wanted to order one soon, but noticed they are out of stock on the website. Link to comment Share on other sites More sharing options...
epleeds March 23, 2011 Share March 23, 2011 this thing is great. I have one set up and it keeps the level perfect. Link to comment Share on other sites More sharing options...
Steve Ramos April 19, 2011 Share April 19, 2011 I saw your ATO in action at the Spring social event and was very impressed. I was going to buy one right there but you guys mentioned an updated ATO with a back-up float valve that will be out soon. When do you think this will be available? Thanks! Link to comment Share on other sites More sharing options...
ctenophore April 23, 2011 Author Share April 23, 2011 Hi Steve We're still testing the backup valve, but the current ATOs come with the new bracket that will hold the valve when available. The valve will be a $15 option for all ATO owners, whether old style (you'll get a new bracket too) or new style. We're not leaving anyone out for the upgrade Justin Link to comment Share on other sites More sharing options...
quazi April 23, 2011 Share April 23, 2011 As much as I like this pressure switch, it has a major problem: the air tube pulls off the switch too easy. I was moving around electric wires, and it came off. Thank God I noticed it after a couple of hours. I am not sure what can be done about it, but it is a problem. Link to comment Share on other sites More sharing options...
FearTheTerps April 23, 2011 Share April 23, 2011 zip ties? Link to comment Share on other sites More sharing options...
Origami April 23, 2011 Share April 23, 2011 Zip ties, after the fact. Maybe a change to a barbed fitting in the design? Link to comment Share on other sites More sharing options...
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