Aquarium Project

[jbradshaw 3]

Hi, I just purchased an A1S cpu and io rack, and am looking for sources to find sensors for water quality. if anyone can direct me to where I could find either analog sensors, or 'smart' sensors with user defined setpoints for alkalinity/ph, calcium concentration, ammonia, nitrates/nitrites, etc. I would appreciate it. Or any other info for sourcing unusual sensors. I figure the rack will handle the timers for the lighting system, and tidal pumps quite nicely. I figure the cpu has plenty of leftover processor to handle simple monitoring. any ideas for cheap hmi's for displaying values? I have looked at an automation direct unit with a serial/power interface added on, that looks like a retail of around $180 USD, are there better solutions for the budget minded user such as myself? the rack w/ cpu and io cards was $100 so I'm trying to find a reasonably priced solution Thanks, John.

[Crossbow 295]

If you got the PLC for $100, I would expect Ebay was involved, and they also could be involved in the HMI hunt.

[roscho 0]

here try this link http://www.omega.com/green/ph.html you can also try automation direct for a micro c-more

[jbradshaw 3]

Thanks, that's the kind of info I'm looking for. I've seen Omega stuff around, I don't know why I didn't think of them myself. I've thought about the Automation Direct, and is probably what I'll use. Thanks again! John.

[Colin Carpenter 10]

If you're thinking of trying to control PH by dosing acid or alkali, it can be a bit of a nightmare. Unlike most sensors, PH is not linear, it's logrythmic (sp?), which means that for a given flow, you have to add 10 times as much to go from PH8 to PH9 as you do to go from PH7 to PH8. Never did get enough time playing with the system to really work it out, unfortunately ...

[jbradshaw 3]

I don't want to dose automatically, I'm mainly looking for measurements so i can trend the data myself, and dose accordingly. John.