Digital Aquatics Reefkeeper Temperature Probe Replacement - DIY?

[Jason777]

Thanks @nub I've tried dragging the sliders on the graphs and I can get to the current readout but as soon as I let go of the left click or move the cursor a micrometer further it jumps back to the previous week. The main problem is when I'm in a custom graph with both displays. If I go to the standard module graph I can scale down to day or hour but it won't let me customize the graph Y axis. Looking at a 0-100° scale doesn't give me much detailed information.

@n2585722 The problem is almost certainly with my SLX module. The module has a spare pH probe attached so I pulled up the graph for it and there are identical spikes. Before seeing the pH probe spikes my thought was possible noise on the wire also and I moved it away from all other cables. Also, thinking it could be a bad connection from where I made up the connector on the first probe, I made a different connector for the second probe. The fact that both pH and temp are spiking at the exact same time makes me think it's the module. There is a very small possibility it could be a bus cable but I doubt that since the SLX is last in line and if it's a bad bus cable everything upstream should be affected. This weekend I will try to troubleshoot some more. After seeing your graphs and pictures I'm much more confident in the new probes so I'll just switch one out with my DA probe on the SL2 module and watch it for a while.

Trying to read through the spikes in my graph it looks like the first probe I bought worked as well as the second. In case anybody else would like to try the plastic encased instead of stainless I'll post the link:
https://smile.amazon.com/gp/product/B07B3VLVQ5/ref=oh_aui_detailpage_o08_s00?ie=UTF8&psc=1

 

[n2585722]

What firmware version do you have on that module?

 

[Jason777]

The SLX is running 2.03

 

[n2585722]

I will check what I have when I get home.

 

[n2585722]

2.03 is what I have also. Do you have a SID and myReef? If so check documents/Digital Aquatics/30-0042 folder and see if you have the file SLX-1-0203.hex. If not then PM me with your email and I will send it to you and you can try a firmware update.

 

[Jason777]

2.03 is what I have also. Do you have a SID and myReef? If so check documents/Digital Aquatics/30-0042 folder and see if you have the file SLX-1-0203.hex. If not then PM me with your email and I will send it to you and you can try a firmware update.

Thanks, I'll check it tonight or tomorrow. My DT is running a RKE and I have a RKL on an AIO tank. This weekend I plan to change the connector on the RKL iTemp and move it so I can have access to all the modules without unplugging something. That should also give me a chance to look at that SLX module on the AIO and let it graph for a while. During that time I'll change over the DT probe to one of the new ones since I will be there to monitor it closely. I've also ordered some wire and connectors so I can make custom length bus cables and do away with the jumbled mess of wires using the stock ones, something I should have done long ago.

 

[n2585722]

Just make sure you get the connectors on correctly.

 

[Jason777]

Here is a quick update for anybody following along. The NTC 10k thermistors seem to work well as replacements for the DA temp probe. I've decided to make some small pigtail adapters to go from the Molex connectors on the RK modules to the JST connectors that come on the thermistors to make change-out simpler. That little pigtail project has delayed much of my testing while waiting on parts from China. The one stainless steel probe I've tried drifted off temperature by about 2° after about a week. The plastic probe has been working well and it has been controlling my AIO tank for almost a month with no noticeable problems. Once I get the adapters made I can do some further testing and comparing but that will most likely be next month.

 

[n2585722]

Here is a quick update for anybody following along. The NTC 10k thermistors seem to work well as replacements for the DA temp probe. I've decided to make some small pigtail adapters to go from the Molex connectors on the RK modules to the JST connectors that come on the thermistors to make change-out simpler. That little pigtail project has delayed much of my testing while waiting on parts from China. The one stainless steel probe I've tried drifted off temperature by about 2° after about a week. The plastic probe has been working well and it has been controlling my AIO tank for almost a month with no noticeable problems. Once I get the adapters made I can do some further testing and comparing but that will most likely be next month.

Thanks for the update. I still have my stainless steel probe controlling my primary heater. So far it seems to be tracking. It could be that on some the epoxy may not be completely sealed. I have one I added some tubing over the probe and wires to keep water from the epoxy. I have not got around to installing it in place of the other probe yet.

 

[Jason777]

Thanks for the update. I still have my stainless steel probe controlling my primary heater. So far it seems to be tracking. It could be that on some the epoxy may not be completely sealed. I have one I added some tubing over the probe and wires to keep water from the epoxy. I have not got around to installing it in place of the other probe yet.

You're probably right about the epoxy leaking and with the pack of 5 there should be no problem finding one that works but I will be adding some extra epoxy like you did. The plastic covered one that I'm using in the AIO is the one that I embedded into epoxy trying to increase the mass and reduce the sensitivity. I didn't see a noticeable change in the sensitivity but it's been working great.
I've run out of pins to make the Molex connectors and just ordered some more so it will be at least next week before I can do more testing.

 

[n2585722]

I switched out the sensor with the one I modified. I did a single point calibration. So far it is tracking with the one on the SL2 module.

 

[JayBABQ]

My stainless has be running really stable right along with the OEM probe. However the probe is starting to rust so watch out. I'll be pulling mine and either using an epoxy one or cover a new one with something. @n2585722 did you cover one? I think I missed it if you did.

 

[n2585722]

My stainless has be running really stable right along with the OEM probe. However the probe is starting to rust so watch out. I'll be pulling mine and either using an epoxy one or cover a new one with something. @n2585722 did you cover one? I think I missed it if you did.

I just added tubing to the back of the probe to keep water from getting to the epoxy. The probe I removed had a film of bacteria growing on it but it cleaned right off.

 

[Jason777]

Parts from Digi-Key will be here today and I will be able to make the wire adapters for quick disconnect and change out of the thermistors. One option I considered was a slightly larger tubing around the thermistor and then filling it with aquarium silicone. The plastic covered thermistor that I embedded in 2 part epoxy putty has been working on my AIO without any problems so I suspect the added insulation would be negligible. Sealing the thermistor in clear aquarium sealant and clear tubing would allow some monitoring and could probably be done with the bare thermistor eliminating the stainless or plastic cases. I've got another plastic covered thermistor, along with the stainless steel ones, and hope to test them against each other once I get the quick connects made.

 

[Jason777]

Things are looking up. I've made a couple of adapters to convert the DA Molex microfit connectors to the JST that the probes use. This will make for easy change out for testing but will likely not be used long term as it will introduce another point of possible failure. With @JayBABQ seeing some rust on his stainless probe I'm concentrating on the plastic waterproof probe. Here's a link to the plastic probe I'm currently testing;
https://smile.amazon.com/gp/product/B07B3VLVQ5/ref=oh_aui_detailpage_o03_s00?ie=UTF8&psc=1
The adapter was made from Molex parts from Digi-Key and JST connectors purchased from Ebay.
This is the adapter and plastic probe I'm currently testing.

Here is a graph of the probe in the first 24 hours. The "NewT SLX" is the plastic probe on my SLX module and "DA T SL2" is the original DA probe on my SL2 module. In this graph the DA probe is controlling the tank which I believe makes for a slightly more perfect plot since it's actually controlling the heater. These are running off an RKE and the heater is set to 76.0 with a hysteresis of 0.1.

The downward spikes on the top chart are due to a problem with the SLX and MyReef software on my laptop. Both of my SLX modules, one on my RKE and one on my RKL give these spikes but it does not appear to affect control.
This morning I swapped the probes putting the new plastic one in control of the tank on the SL2 module and the DA probe on the SLX module and I will upload another graph for comparison in the next day or two.

 

[JayBABQ]

That is great news. I ordered those probes the other day, should be here Wednesday. Thanks for the find and the testing.

 

[Jason777]

Here are the results with the new plastic probe on the SL2 module controlling the heater. These graphs are 24 hour and started around 11am.

It would be easier to understand if the downward spikes were not there but you can see that it's the SLX module and not the probe causing them. This graph has the DA temp probe on the SLX and new probe on the SL2. It looks like the new probe is more sensitive than the DA probe. There is also going to be a slight difference because the calibration between the two probes will never be exact. Even with the new probe showing a little more variance in temperature you can see that this is not a real difference when compared to yesterdays chart with the DA probe controlling on the SL2.
For now, I'm going to swap the probes back where the DA will be controlling the tank and let the plastic probe run for a while to make sure there is no drift or premature failure. This same type plastic probe has been controlling my AIO tank for about a month with no problems but it is encased in epoxy.
When I get some time I'll swap the plastic probe for one of the stainless probes so there will be a chart of it to compare.

 

[andrewprime1]

This might be a stupid question... But how are you guys hooking these probes up to your RK? My temp probe finally died after ears of faithful service and I am looking for a solution, fast! I bought the probes that Jason777 is testing and I am thinking I am just gonna have to splice in the male connector from my old DA probe. It looks like an RJ11 terminal, can I just buy some phone cable ends from home depot on crimp the in?

 

[andrewprime1]

This might be a stupid question... But how are you guys hooking these probes up to your RK? My temp probe finally died after ears of faithful service and I am looking for a solution, fast! I bought the probes that Jason777 is testing and I am thinking I am just gonna have to splice in the male connector from my old DA probe. It looks like an RJ11 terminal, can I just buy some phone cable ends from home depot on crimp the in?

 

[n2585722]

This might be a stupid question... But how are you guys hooking these probes up to your RK? My temp probe finally died after ears of faithful service and I am looking for a solution, fast! I bought the probes that Jason777 is testing and I am thinking I am just gonna have to splice in the male connector from my old DA probe. It looks like an RJ11 terminal, can I just buy some phone cable ends from home depot on crimp the in?

You can use RJ12 connectors. It has to be the six conductor ones. Make sure you get the wires in the correct contacts on the connector.