Opinions on current Atlas Scientific hardware

[Dennis Cartier]

Hey reef-Pi users. I am considering purchasing a bunch of Atlas Scientific boards for a custom build I have underway (non Reef-Pi). I have used the Atlas Scientific stuff in the past, but it was before they had electrical isolation support built in, and the results were fairly terrible at that time. The pH, EC and ORP were all unstable and unusable in an aquarium (at that time). I am curious for feedback from any Atlas Scientific users who have used their stuff since the inclusion of the electrical isolation support. Especially for EC and pH. I will be including ORP at a later time, so feedback on ORP welcome as well.

The Atlas Scientific stuff adds up quickly, and I would rather not waste any more funds on them if they are still not up to the task. So please provide feedback if you have used them.

Dennis

 

[GoVols]

@Ranjib

Do you have any incite?

Thank you

 

[Ranjib]

Thank you for tagging @GoVols

I have been using atlas scientific probes with galvanic isolation for 3+ years now and been very happy with it. If you are not using galvanic isolation, it is expected to have unstable reading, and I suspect that's the reason for your bad experience with their probe. Overall pH setup for atlas should cost 100$+ USD (probe + carrier board with galvanic isolation).

 

[Dennis Cartier]

Thank you for tagging @GoVols

I have been using atlas scientific probes with galvanic isolation for 3+ years now and been very happy with it. If you are not using galvanic isolation, it is expected to have unstable reading, and I suspect that's the reason for your bad experience with their probe. Overall pH setup for atlas should cost 100$+ USD (probe + carrier board with galvanic isolation).

Have you used their EC probes per chance? I am curious if they are reliable in their readings and accuracy. I know the Neptune EC module had a bad rep of being off a lot. I am hoping that the Atlas ones are more trustworthy.

Dennis

 

[Ranjib]

I have not , but I think your problem is likely from your setup /calibration and unrelated to atlas scientific probes or circuit as they are very reputed beand across academic , industry and hobbyist . We’ll definitely hear bad things if their probes /circuit are not reliable. the problems you are mentioning are also very common and known.

EC probes have higher calibration requirement, including temperature compensation. They are known for giving errornous reading in absence of those . @eag has a detailed post in r2r on how to calibrate EC probe. I think your EC probe reading will stabilize if you follow the equivalent calibration process

 

[Dennis Cartier]

I have not , but I think your problem is likely from your setup /calibration and unrelated to atlas scientific probes or circuit as they are very reputed beand across academic , industry and hobbyist . We’ll definitely hear bad things if their probes /circuit are not reliable. the problems you are mentioning are also very common and known.

EC probes have higher calibration requirement, including temperature compensation. They are known for giving errornous reading in absence of those . @eag has a detailed post in r2r on how to calibrate EC probe. I think your EC probe reading will stabilize if you follow the equivalent calibration process

Any issues I had in the past with them were more than a decade ago, when they did not have galvanic isolation and were not really used on aquariums. I have not purchased any of their newer equipment, but I am about to.

I am somewhat familiar with how EC probes work. I have a few different models of Thermo Scientific meters that I use for manual testing. Those come in 2 and 4 electrode versions and include temperature sensors right in the probe, so you don't need to feed the temperature into the call like you do/did with the AS hardware. We will see how the AS probes compare to those once I have them in hand.

Dennis

 

[MaddyP]

Atlas Ezo modules have been great in my Node-Red controller. I’m running pH, ORP, EC, humidity, and temp. Isolation seems stable for my setup running with no noticeable deviation of reading when items in my cabinet click on/off. Wires aren’t right next one another but closer than I’d like considering the tight space with which I am working.

 

[Ranjib]

Any issues I had in the past with them were more than a decade ago, when they did not have galvanic isolation and were not really used on aquariums. I have not purchased any of their newer equipment, but I am about to.

I am somewhat familiar with how EC probes work. I have a few different models of Thermo Scientific meters that I use for manual testing. Those come in 2 and 4 electrode versions and include temperature sensors right in the probe, so you don't need to feed the temperature into the call like you do/did with the AS hardware. We will see how the AS probes compare to those once I have them in hand.

Dennis

Makes sense. Keep us posted on your experience with the new setup

 

[Dennis Cartier]

Ok, the order is in. It cost me exactly 10 bits! Let's hope it is a good omen.

 

[Ranjib]

Ok, the order is in. It cost me exactly 10 bits! Let's hope it is a good omen.

Godspeed. I just checked, ph kits are now 179$ usd. Sticker shock !!!

 

[theatrus]

Godspeed. I just checked, ph kits are now 179$ usd. Sticker shock !!!

Ouch, thats a pretty big premium, didn't realize those had bumped up that high. It does at least include the probe.

 

[robsworld78]

Godspeed. I just checked, ph kits are now 179$ usd. Sticker shock !!!

Wow, you can get a Robo-Tank with Pi, SD card and double junction probe for same price.

 

[Dennis Cartier]

Wow, you can get a Robo-Tank with Pi, SD card and double junction probe for same price.

With the way Pi prices are going, soon it will be you are paying for the Pi and getting a Robo-Tank, SD card and double function probe for free!

 

[Ranjib]

Price was one of the major reason for the opensource ph board. It cuts down price by 1/3rd. since the adc+isolation package+bnc connector all included in 50$. That was a great work from Roberto Buti (italian, iirc).

 

[robsworld78]

With the way Pi prices are going, soon it will be you are paying for the Pi and getting a Robo-Tank, SD card and double function probe for free!

No kidding hey, thankfully the Zero 2 is still cheap if you're willing to backorder. I started stocking these just so people can still get a controller.

 

[theatrus]

No kidding hey, thankfully the Zero 2 is still cheap if you're willing to backorder. I started stocking these just so people can still get a controller.

Yeah, a few distributors definetly put max order sizes, Newark hasn't been one.

 

[robsworld78]

Yeah, a few distributors definetly put max order sizes, Newark hasn't been one.

Same with Digi-key, you can only order 2 when you add to cart but you can add two five times.

 

[Dennis Cartier]

Hey @MaddyP , are you seeing any variation in the EC readings from your probe? E.g. if you take 10 readings in a row, are they all steady or do they vary by 10's or 100's of uS?

Here is what I have found so far with the new Atlas Scientific hardware.

I purchased a couple of T3 boards along with 2 mini EC probes (K 1.0), 2 RTD temperature sensors and a pH probe. I also purchased enough of the probe holders to mount each probe (except the RTD sensors).

To test the EC probes, I whipped up a manifold that could be inserted into the existing water line feeding a fuge barrel and my CaRx. What I found that one of the EC probes was kind of stable, but the other one would constantly drift higher. I also noticed the somewhat stable one would lose it's accuracy at the edges of the temperature swing. I hypothesized it was caused by the distance the RTD sensors were from the actual probes themselves. The RTD sensors were in the sump, close to a heater, where the probes were several feet away.

One thing that I noticed was that the mini EC probes are too short to reach pass the probe holder body, into the tee that the probe holder is mounted on. That made me think that perhaps that was part of the issue. So I ordered another full sized EC probe (along with EC module).

When the new parts arrived, I created a new manifold from scratch, with space for the 3 EC probes along with the 2 RTD sensors. I had noticed that the RTD sensors were close enough to 1/4" to push into John Guest style fittings and not leak. So I included 2 1/4" ports in the manifold.

I started testing the new install and noticed that the RTD probes were reading 22.5C instead of the 25.nnC that I was expecting. The 3 EC probes were also reading off. The 2 mini probes had similar readings to each other, and the full sized one varied from the mini's, but was still off. After taking the manifold apart, I determined that the RTD sensors could not push far enough into the fitting to sense the water temperature, and the 22.5C I was seeing was the temperature of the manifold.

To correct for the temperature issue, I moved the sensors into the fuge, where the water flowing past the EC probes was ending up. While doing this, the EC readings suddenly shifted to being much closer to the expected range. After a few more tweaks to my code, the EC readings again became way out of range. It turned out that by 'fixing' my code to feed the current real temperature into the EC modules (instead of an override I had in place), the mini probes lost accuracy and the full sized probe lost partial accuracy. I found that if I overrode the temperature for the mini probes to 22.5C (what they were using when the RTD sensors were in the manifold), they again functioned closer to normal. I concluded that there was a thermal effect between the probe holder and the mini EC probe.

I reached out to Atlas Scientific and spoke to Efrem. His response, that this was not observed in any other installs, and that the EC probes are the probes that give them the least problems (install it, calibrate it, done), gave me reason for pause. Whenever I find that I have results that match no one else, it usually means I have done some thing wrong, lol.

I have moved the probes out of the manifold and have them in my sump along with the RTD sensors. The are fairly stable. The 2 mini probes are usually pretty close to each other in readings, while the full sized one is higher, normally. Also the full sized probe that was added last, about 2 weeks after the mini's were installed, drifted higher over a week or so, but has stopped drifting now. My gut says that a deposit forms on the electrode surface over time and affects the readings. I have not confirmed this yet, but may pull one of the probes out and run an alcohol wipe through the measurement hole. Previously I was cleaning the measurement hole with an alcohol wipe before each calibration. When I stopped, was when I noticed they seemed to stop drifting higher.

I am not sure what causes the noise in the readings. I read each probe 10 times, calculate the variance on the readings for each probe, remove the outliers, and calculate the average. I am using Widgetlord's SPI boards on the same RPI, but so is MaddyP. So I am unsure if it is interference from the SPI boards or driver. I upgraded to a 5A Meanwell DIN power supply just in case it was power related, no effect. At some point I plan to pull the probes out to a separate vessel and see if the readings become more constant. This still could be a voltage leak in the tank or some other interference. I have a Thermo Scientific bench top meter with a 4 electrode probe also measuring the tank, and it does not show any instability. Though it only shows 1 decimal place (E.g. 53.3) where I am rounding the AS probes to 3 decimal places, so that may partially account for the difference.

During this process, I found that when a critter crawls across the electrode's reading surface, it really messes with the results. Having 3 probes online at the same time makes it possible to detect and remove that probe from the current sensor polling. I am not sure what people do if they only have 1 probe when this happens?

Tomorrow I plan to start adding salinity control to combat the overly large surface area of my (stock tank) sump as compared to the smaller frag tank it is on. Even with the noise in the readings, the combination of the 3 probes keeps the readings within 200 uS of the readings I get with my TM HP hydrometer. Which I test with frequently so that I can perform a 'soft' calibration on the EC probes if needed.

 

[MaddyP]

Hey @MaddyP , are you seeing any variation in the EC readings from your probe? E.g. if you take 10 readings in a row, are they all steady or do they vary by 10's or 100's of uS?

Here is what I have found so far with the new Atlas Scientific hardware.

I purchased a couple of T3 boards along with 2 mini EC probes (K 1.0), 2 RTD temperature sensors and a pH probe. I also purchased enough of the probe holders to mount each probe (except the RTD sensors).

To test the EC probes, I whipped up a manifold that could be inserted into the existing water line feeding a fuge barrel and my CaRx. What I found that one of the EC probes was kind of stable, but the other one would constantly drift higher. I also noticed the somewhat stable one would lose it's accuracy at the edges of the temperature swing. I hypothesized it was caused by the distance the RTD sensors were from the actual probes themselves. The RTD sensors were in the sump, close to a heater, where the probes were several feet away.

One thing that I noticed was that the mini EC probes are too short to reach pass the probe holder body, into the tee that the probe holder is mounted on. That made me think that perhaps that was part of the issue. So I ordered another full sized EC probe (along with EC module).

When the new parts arrived, I created a new manifold from scratch, with space for the 3 EC probes along with the 2 RTD sensors. I had noticed that the RTD sensors were close enough to 1/4" to push into John Guest style fittings and not leak. So I included 2 1/4" ports in the manifold.

I started testing the new install and noticed that the RTD probes were reading 22.5C instead of the 25.nnC that I was expecting. The 3 EC probes were also reading off. The 2 mini probes had similar readings to each other, and the full sized one varied from the mini's, but was still off. After taking the manifold apart, I determined that the RTD sensors could not push far enough into the fitting to sense the water temperature, and the 22.5C I was seeing was the temperature of the manifold.

To correct for the temperature issue, I moved the sensors into the fuge, where the water flowing past the EC probes was ending up. While doing this, the EC readings suddenly shifted to being much closer to the expected range. After a few more tweaks to my code, the EC readings again became way out of range. It turned out that by 'fixing' my code to feed the current real temperature into the EC modules (instead of an override I had in place), the mini probes lost accuracy and the full sized probe lost partial accuracy. I found that if I overrode the temperature for the mini probes to 22.5C (what they were using when the RTD sensors were in the manifold), they again functioned closer to normal. I concluded that there was a thermal effect between the probe holder and the mini EC probe.

I reached out to Atlas Scientific and spoke to Efrem. His response, that this was not observed in any other installs, and that the EC probes are the probes that give them the least problems (install it, calibrate it, done), gave me reason for pause. Whenever I find that I have results that match no one else, it usually means I have done some thing wrong, lol.

I have moved the probes out of the manifold and have them in my sump along with the RTD sensors. The are fairly stable. The 2 mini probes are usually pretty close to each other in readings, while the full sized one is higher, normally. Also the full sized probe that was added last, about 2 weeks after the mini's were installed, drifted higher over a week or so, but has stopped drifting now. My gut says that a deposit forms on the electrode surface over time and affects the readings. I have not confirmed this yet, but may pull one of the probes out and run an alcohol wipe through the measurement hole. Previously I was cleaning the measurement hole with an alcohol wipe before each calibration. When I stopped, was when I noticed they seemed to stop drifting higher.

I am not sure what causes the noise in the readings. I read each probe 10 times, calculate the variance on the readings for each probe, remove the outliers, and calculate the average. I am using Widgetlord's SPI boards on the same RPI, but so is MaddyP. So I am unsure if it is interference from the SPI boards or driver. I upgraded to a 5A Meanwell DIN power supply just in case it was power related, no effect. At some point I plan to pull the probes out to a separate vessel and see if the readings become more constant. This still could be a voltage leak in the tank or some other interference. I have a Thermo Scientific bench top meter with a 4 electrode probe also measuring the tank, and it does not show any instability. Though it only shows 1 decimal place (E.g. 53.3) where I am rounding the AS probes to 3 decimal places, so that may partially account for the difference.

During this process, I found that when a critter crawls across the electrode's reading surface, it really messes with the results. Having 3 probes online at the same time makes it possible to detect and remove that probe from the current sensor polling. I am not sure what people do if they only have 1 probe when this happens?

Tomorrow I plan to start adding salinity control to combat the overly large surface area of my (stock tank) sump as compared to the smaller frag tank it is on. Even with the noise in the readings, the combination of the 3 probes keeps the readings within 200 uS of the readings I get with my TM HP hydrometer. Which I test with frequently so that I can perform a 'soft' calibration on the EC probes if needed.

No, I haven’t had any issues with mine. Reading is super stable once it was in the tank about two weeks. In fact, it’s so stable the only time it varies is when I top off each morning.

 

[Dennis Cartier]

No, I haven’t had any issues with mine. Reading is super stable once it was in the tank about two weeks. In fact, it’s so stable the only time it varies is when I top off each morning.

Hmm, another result that suggests the issue is local to me. I will have to look for a local cause. Though as time goes on, it seems like the instability is decreasing. I also noticed that it took about 2 weeks for the constant creep higher in readings to moderate.

I also may be mistaking sensitivity for instability. I read the probes every 5 minutes and I noticed that when I get a jump of +/-100 uS from the previous reading, it seems to affect all the probes equally.

Hmm, more testing needed.