Reef-pi DS18B20 Error Handling

[NeonRabbit221B]

So I have built a few reef-pis for my collection of tanks and they work very well for the most part. A perfect union of my two favorite hobbies and is quite honestly how I got into reefing in general. When I started my first reef tank, I moved my reef-pi from my freshwater to saltwater tank and a couple weeks later the saltwater ate through the sensor. It took me a while to figure it out but after a few scares of my heater kicking on when the sensor returned a value of "0" and staying on I have been nervous about allowing the probe to control the heater. I also have alerts setup and every now and then I get a nice email saying my tank is 185 degrees.

I know what these errors are likely attributed to but after trying new sensors, going over it with a multimeter, doing shorter wire paths, adjusting resistors, trying different coatings for the sensors and such I still get the occasional email from an error. Its not only with my older sensors but occasionally it happens with new replacements. Its intermittent and frustrating.

Any tips on correcting this? I have honestly tried every trick I have read from every posting I could find.. If there a way to simply toss out these bad readings that are occasional? Any way to have an error counter to alert me when a sensor is pretty dead?

Otherwise fantastic project and I honestly wish I had the knowledge and ability to help with changes.

 

[Ranjib]

I use canakit and adafruit sensors only and only encountered this issue twice or thrice in past three n half years. I'd recommend starting with a good vendor (drok, adafruit, canakit) and seal the sensor if needed. None of my sensor got rust yet, the canakit ones have black powder coating which makes them even better for saltwater use

All this said, I think we have to do a better job on the software side also to deal with such error. I'll keep this in mind and probably push some safety nets around this in 3.0, but no promise
Thank you so much for trying out reef-pi and taking the time to write down your inputs/observations

 

[NeonRabbit221B]

Thank you so much for the tip and all of your hard work. I was hoping I was missing something in Macros or an options. I did find this which I have not tried but will tonight. My issues are very much related to timing and responses.

4 tanks with 2 sensors each is expensive to go for premium parts but I will try the canakit ones.

 

[Ryan115]

After having an issue with the "stainless" DS18B20 probes, I switched to the epoxy coated ones from Sparkfun. https://www.sparkfun.com/products/11050
I believe someone just had an issue with one of the DROK sensors rusting through as well, but not sure I remember exactly what happened.
Additionally, if you are concerned about the temp control. You can set the heater thermostat to be the primary control and have reef-pi cut the power to the heater if it gets too hot.

 

[Bigtrout]

So I have built a few reef-pis for my collection of tanks and they work very well for the most part. A perfect union of my two favorite hobbies and is quite honestly how I got into reefing in general. When I started my first reef tank, I moved my reef-pi from my freshwater to saltwater tank and a couple weeks later the saltwater ate through the sensor. It took me a while to figure it out but after a few scares of my heater kicking on when the sensor returned a value of "0" and staying on I have been nervous about allowing the probe to control the heater. I also have alerts setup and every now and then I get a nice email saying my tank is 185 degrees.

I know what these errors are likely attributed to but after trying new sensors, going over it with a multimeter, doing shorter wire paths, adjusting resistors, trying different coatings for the sensors and such I still get the occasional email from an error. Its not only with my older sensors but occasionally it happens with new replacements. Its intermittent and frustrating.

Any tips on correcting this? I have honestly tried every trick I have read from every posting I could find.. If there a way to simply toss out these bad readings that are occasional? Any way to have an error counter to alert me when a sensor is pretty dead?

Otherwise fantastic project and I honestly wish I had the knowledge and ability to help with changes.

My sensors were flawless...then I had a led lighting power supply go bad, it was strange as it still ran the lights but something caused it to throw some big time emi, got the random 185f and sometimes a big negative reading. Turned out that one of my led power supplies was bad and even though it was nowhere near the temp sensors, nor hooked to the pi, it was affecting everything on my pi especially the ph probe. It also caused my cable modem to give lots of uncorrectable packet errors. New power supply solved all my problems and I havent had a bad reading since.

Look for sources of intereference if all wiring and connections have checked out as good. Is the temp sensor near a wire from a 'noisy' device like a pump or motor, etc?

 

[NeonRabbit221B]

I honestly think I tried every trick in the book except the epoxy/powder coated sensors. I order some from canakit. Hope it works because I have another sensor failing now. I did a thin layer of silicon which has held up pretty well (about 6 weeks).

 

[NeonRabbit221B]

After having an issue with the "stainless" DS18B20 probes, I switched to the epoxy coated ones from Sparkfun. https://www.sparkfun.com/products/11050
I believe someone just had an issue with one of the DROK sensors rusting through as well, but not sure I remember exactly what happened.
Additionally, if you are concerned about the temp control. You can set the heater thermostat to be the primary control and have reef-pi cut the power to the heater if it gets too hot.

This is a good idea I didn't think of. Thank you!

 

[Kuikui]

Hi,

Everytime I used the epoxy-sealed DS18B20, the sensor finally stopped working after a few months (between 6 to 12 months).
This sensor does not seem to be "waterproof", but only to be used " in wet environments".

The problem about this is that I think the probe gets corroded from inside, and metal ions finally get into water, which is very bad for our fish and corals.

The only solution that I think may work is to seal the probe with aquarium silicon all around it.. but not tested yet.

 

[attiland]

Hi,

Everytime I used the epoxy-sealed DS18B20, the sensor finally stopped working after a few months (between 6 to 12 months).
This sensor does not seem to be "waterproof", but only to be used " in wet environments".

The problem about this is that I think the probe gets corroded from inside, and metal ions finally get into water, which is very bad for our fish and corals.

The only solution that I think may work is to seal the probe with aquarium silicon all around it.. but not tested yet.

Many does it. Makes the probe slower but for the application it is not that important.

 

[theatrus]

Many of the metal crimped on probes are ... not well sealed, or potted, etc. If you can coat it in plastic/silicone/epoxy, or find a plastic encapsulated version, all the better.

The cheap DS18B20 probes also aren't the real thing. They're usually ok, but sometimes way off or marginal.

I did cook up some fully potted plastic encapsulated sensors awhile back. No way I can compete with the cheap sensors, but they are an option: