reef-pi :: An opensource reef tank controller based on Raspberry Pi.

[Ranjib]

Talking about temperature sensors.. I am doing some experiments with the heaters internal thermostat vs reef-pi controls and I am not very happy with the heater's internal control. Particularly for pico tanks this might be a problem. I am observing almost 1 degree temperature swings in 30 min period

I wanted to observe the results for several days before posting here. This is the dashboad of my 29G biocube, with a Eheim 100W jaeger heater in it. It was controlled by reef-pi till 1st Feb. Initially I played with reef-pi's internal temperature controller to check if i can dial down exact temperature (79.5, 79.6, 79.3 etc) and then with reef-pi configured to only monitor and let the heater's internal control do the on/off. The results are not very satisfactory. I'll be using the the heater's temperature graph to implement hysteresis in reef-pi (sane defaults).
Here is the dashboard of my pico tank (3.7G, with 25W aqueon heater)

Irrespective of the observations, I am excited about this data, I think we can pin down such behaviors across tank volume and heater types (wattage and brand) and hopefully push the boundary of what temperature stability means in reef tanks

 

[Ranjib]

How much wire length and what size pull-up?

ReefPi should probably do retries at some level instead of reporting bogus values

we do check CRC code/checksum. any reason for you to think that we are reporting bogus value? or any checks we should be making?
I have thoughts about using moving average and auto correcting anomolous values.. but not for current releases (3.0)

 

[Ranjib]

reporting back on the memory issue, not seeing it in all of my builds. I am running 2.1 where this should be visible. There are some cases where I can see the jump, but its not necessarily due to leak, and its not fatal. Here is a dashboard of ph monitor running for almost 3 weeks continuously now. I dont keep the dashboards open .. so thats a factor which is not tested

 

[Ranjib]

Here is another test build (the one running in the garage with a 5.5 G test tank) dashboard. This has two ato sensors, and three temperature sensors (two inside, one outside the tank)

 

[Bigtrout]

Talking about temperature sensors.. I am doing some experiments with the heaters internal thermostat vs reef-pi controls and I am not very happy with the heater's internal control. Particularly for pico tanks this might be a problem. I am observing almost 1 degree temperature swings in 30 min period

I wanted to observe the results for several days before posting here. This is the dashboad of my 29G biocube, with a Eheim 100W jaeger heater in it. It was controlled by reef-pi till 1st Feb. Initially I played with reef-pi's internal temperature controller to check if i can dial down exact temperature (79.5, 79.6, 79.3 etc) and then with reef-pi configured to only monitor and let the heater's internal control do the on/off. The results are not very satisfactory. I'll be using the the heater's temperature graph to implement hysteresis in reef-pi (sane defaults).
Here is the dashboard of my pico tank (3.7G, with 25W aqueon heater)

Irrespective of the observations, I am excited about this data, I think we can pin down such behaviors across tank volume and heater types (wattage and brand) and hopefully push the boundary of what temperature stability means in reef tanks

I agree, and this is alot more important in smaller tanks..I tested my pair of aqueon pros on their own co trol in my 75 and only see a variation of .2 to .3 degrees F over the course of a day, and that is directly related to room temperature(keep the house a few degrees cooler at night)
Because they have accurate solid state controls, reef pi is set up as my failsafe to shut them off if one runs away stuck ON.

 

[Mikeneedsahobby]

With reef pi set at 60s checks. I don’t see any real temp change on either tank.

With the heater controlling the 20g freshwater I had 3.5 degrees of spread. Interval was about an hour. On my 75g salt. I see 3 degrees and a period of 1.75 hrs.

I plan to try longer periods on the pi to get about 0.5 degree of spread.

 

[daveCB]

we do check CRC code/checksum. any reason for you to think that we are reporting bogus value? or any checks we should be making?
I have thoughts about using moving average and auto correcting anomolous values.. but not for current releases (3.0)

The error value always went high and then recovered. The value would go from 78 to 180 and then back to 78 at the next pass. There was no time that the erroneous value was more than one cycle.

As for the length, it’s 3 meters. Certainly within range of the pull-up.

Now that the cycle is 30 seconds, there are zero errors in 13 hours.

 

[Ranjib]

The error value always went high and then recovered. The value would go from 78 to 180 and then back to 78 at the next pass. There was no time that the erroneous value was more than one cycle.

As for the length, it’s 3 meters. Certainly within range of the pull-up.

Now that the cycle is 30 seconds, there are zero errors in 13 hours.

Thats is a very good detailed information. Thank you for sharing. I'll read the ds18b20 docs again. I can recall encountering things like this couple of times in the very beginning, pre 1.0.. but nothing in past couple of years.

 

[Bigtrout]

Thats is a very good detailed information. Thank you for sharing. I'll read the ds18b20 docs again. I can recall encountering things like this couple of times in the very beginning, pre 1.0.. but nothing in past couple of years.

@Ranjib
I did some research and 85C or 185F is the power up default reading of the ds18b20. From my research this points to communication failure most times, and usually ends up being bad cabling. Suggested cabling is twisted shielded. The drok sensors I am using are shielded cables, and I have not seen a problem with the 4 I have. The other suggested cabling is cat 5, which is what @Erica-Renee has suggested.

The 85 degree reading is the power-up state of the DS18B20 & DS1822 sensors see datasheet page 7 http://datasheets.maximintegrated.com/en/ds/DS18B20.pdf. This means that the temperature sensor has either not received an instruction to do a temperature conversion, or it has not had the time or the power to do a conversion.

 

[daveCB]

@Ranjib
I did some research and 85C or 185F is the power up default reading of the ds18b20. From my research this points to communication failure most times, and usually ends up being bad cabling. Suggested cabling is twisted shielded. The drok sensors I am using are shielded cables, and I have not seen a problem with the 4 I have. The other suggested cabling is cat 5, which is what @Erica-Renee has suggested.

The 85 degree reading is the power-up state of the DS18B20 & DS1822 sensors see datasheet page 7 http://datasheets.maximintegrated.com/en/ds/DS18B20.pdf. This means that the temperature sensor has either not received an instruction to do a temperature conversion, or it has not had the time or the power to do a conversion.

I am using the Dronk sensors. I have two implemented on the same one wire. Again, now that the cycle is 30 seconds and not 60 seconds, there are no errors.

 

[Bigtrout]

I am using the Dronk sensors. I have two implemented on the same one wire. Again, now that the cycle is 30 seconds and not 60 seconds, there are no errors.

Do both sensors give the high reading or just one of them

 

[dmolavi]

I am using the Dronk sensors. I have two implemented on the same one wire. Again, now that the cycle is 30 seconds and not 60 seconds, there are no errors.

How do you have both wired up to the same one-wire? I've got 2 of the dronk sensors (just arrived yesterday) and would prefer just one connection if possible. Two might be preferable if I have to swap them out for any reason though.

 

[DirtDiggler2823]

@theatrus @Ranjib , it seems as though pH functionality is right around the corner. Should I assume that it's safe to move forward with purchasing a double junction pH probe?

 

[theatrus]

How do you have both wired up to the same one-wire? I've got 2 of the dronk sensors (just arrived yesterday) and would prefer just one connection if possible. Two might be preferable if I have to swap them out for any reason though.

Simply put, attach all wires in parallel. 1-wire is a multi-device bus and can support multiple devices.

 

[DirtDiggler2823]

How do you have both wired up to the same one-wire? I've got 2 of the dronk sensors (just arrived yesterday) and would prefer just one connection if possible. Two might be preferable if I have to swap them out for any reason though.

Simply put, attach all wires in parallel. 1-wire is a multi-device bus and can support multiple devices.

@theatrus @Ranjib , it seems as though pH functionality is right around the corner. Should I assume that it's safe to move forward with purchasing a double junction pH probe?

I built mine as though they were stand alone, and just used the typical 3.5mm splitter that you would use for headphones. It works well, and it allows me to pull and work on the probes one at a time if need be.

 

[Ranjib]

You can get the probe... but this is software, issues can creep up any time, so nothing is guaranteed till I ship it :-). Also the changes I am making is primarily tested with the ph board, not the base board. That will come later

 

[DirtDiggler2823]

You can get the probe... but this is software, issues can creep up any time, so nothing is guaranteed till I ship it :). Also the changes I am making is primarily tested with the ph board, not the base board. That will come later

@theatrus is working on the baseboards as well. Seems like the two efforts are coming together at around the same time.

 

[daveCB]

Do both sensors give the high reading or just one of them

Both sensors are on the same GOIO pin and are just in parallel. When the error was happening, both went high consistently on the same cycle. About once per hour or so.

 

[lotus02]

I have bin reading all can find on the reef-pi and ordered all the parts just like to ask is any new sketches for the builds as they don't match the pictures as for layout. Trying to read through all 480 plus pages is taking a long time to see if any have bin added. I'm building 3 of these. And I would like to say thank you for all time you have put into it, and for sharing it

 

[Ranjib]

I have bin reading all can find on the reef-pi and ordered all the parts just like to ask is any new sketches for the builds as they don't match the pictures as for layout. Trying to read through all 480 plus pages is taking a long time to see if any have bin added. I'm building 3 of these. And I would like to say thank you for all time you have put into it, and for sharing it

Thank you for considering reef-pi. You dont have to read through this entire thread, most of it is dated and not very relevant (if not incorrect ) for the current version. Start a build thread and let us know your questions, and we'll help you out.