Apex LLS-15 Terrible

[Mr31415]

I have two LLS-15 sensors - one in my sump, the other in my RO container. I have calibrated, recalibrated, reset (toggle the type of LLS sensor trick) etc. - they work for a few months, then stop reading accurately. Specifically, especially the one in the RO reservoir, the sensor would read accurately until it hits about 12cm or so, then it would start climbing - which is impossible as I measured the water level and the RO reservoir only drains, it does not back fill.

So I ended up building a custom water level sensor using an ultrasonic sensor and an ESP12e controller, and some data logging stuff. I was hoping the (expensive) LLS sensor would be functional, but it is just too unreliable for me. I have missed the RO reservoir being empty more than I can count because it never alerted me, and the few times it did (via the Apex programming), it sent a notification to my phone every 5 seconds. There was no hysteresis in the notifications.

The LLS graph is shown below, and below that - the custom ultrasonic sensor. I will be using the latter from now on. Just thought I'd share my experiences as I see many other people also have issues with the LLS sensors.

 

[Formulator]

Neat. Whats the working principle behind the ultrasonic sensor?

My LLS 15 was a pain to get calibrated, but I haven’t had any issues since then. I will need to keep an eye on it as I don’t really have any failsafe to keep it from overflowing my RODI reservoir. Fortunately an overflow of that container wouldn’t be a big deal as it is on a concrete floor near a drain, but still…

 

[Mr31415]

It is a simple ultrasonic sensor like this https://a.co/d/26xjkqE. Every minute my ESP32 microcontroller sends it a signal to fire off an ultrasonic sound pulse which reflects off the water level and the duration this wave takes to traverse the distance (divided by 2) gives you the distance. It is accurate to about 0.3cm - more than enough for what I need it for.

I just saw the LLS-15 did it again - note the difference in level between LLS (top) and Ultrsonic (bottom) starting 26 Aug @ 08:00:

 

[Formulator]

What a great idea! Now how does the microcontroller interface with Apex?

 

[Mr31415]

At this point in time it does not. It would not be too hard to interface it. I however have a separate control system to which it integrates - so it sends me push notifications if the RO level is < 5cm, and it sends its data to influx which goes to grafana and the same panel I monitor my apex from.

 

[braaap]

At this point in time it does not. It would not be too hard to interface it. I however have a separate control system to which it integrates - so it sends me push notifications if the RO level is < 5cm, and it sends its data to influx which goes to grafana and the same panel I monitor my apex from.

Any details on grafana integration with apex? Or do they not? I use grafana for a media server I run but I haven’t really dug too deep into it.

Could this system output 0-10v signals? I have a 15” LLS and it works perfectly. Dead accurate for 6+ months. But I’m swapped to Hydros and only running my apex to control a trident until Maven comes out.

 

[Mr31415]

It is tricky - there is no official API I know of, but there are ways of getting at the data through Fusion.

I did look and it seems like I was mistaken - unless I missed it, it does not seem like my Apex has any generic well documented I/O ports to which you can connect your own electronics. Bummer. My old aquatronica controller could.

As to the ultrasonic sensor I built - it can do whatever one wants. I just happen to have hooked up an LED for low level, RF integration to my controller and WiFi for NTP / time sync.

 

[StickyThwomp]

As to the ultrasonic sensor I built...

If you don't mind a few queries... Any perspective to share on the longevity of that ultrasonic sensor in your ro reservoir? I was looking at doing the same in my closed RO container. I even got a handful and started prototyping, but after a bit more reading I'm concerned that the humidity might get to it and affect readings or eventually cause it to fail entirely.

Was yours added around the time you posted about it? Or have you been running it for a good long while? Is your sensor in open air or closed off in the reservoir itself? Did you consider any other diy full range measurement solutions like capacitive level sensing?

 

[Mr31415]

Can't speak to that yet as I only have it up and running for 2 months - so far no issues. Sensor is in a custom made box, but the actual transmitter and receiver are obviously protruding out.

I am going to upgrade it to use a different sensor that is IP65 rated. But that is mostly for the fact that I got a ReefCan 40 and that is too narrow for the 15 degree beam of the sensor I currently have.

 

[StickyThwomp]

Ty for the response! If you've got any further findings or experience DIYing this, I'd sure love to hear about it! I'm experimenting with a fdc1004 and copper tape for capacitive sensing on the outside of my rodi tank. Only done a small test on a plastic container so far, but once/if I have something with a bit more substance I'm gonna spin up a diy thread about it!

 

[subodhs]

For what it's worth, the LLS is nothing but a fancy gizmo that gives you a reading. It cannot be relied upon for automation as it takes far too long to register level changes—something like 30-60 seconds. It was a pain to get calibrated, but once done, it's been working fine for a quick look. However, I still use the optical level sensors to control the actual automation. Even they fail so I use two of them! The optical sensors can change state almost every second while the LLS hardly registers any change.

I also like what you've done with your DIY sensor and would love to know more. One can probably find a way to integrate it into Apex (unofficially of course) . I tried exploring the various methods (break out boxes, optocouplers, FMM modules) but gave up somewhere as there's much tinkering but not enough to gain as the Apex itself is very ... finicky - not sure if that's the right word. :) I realized the float switch is a lot more reliable and cheaper than most anything.

 

[areefer01]

Any details on grafana integration with apex? Or do they not? I use grafana for a media server I run but I haven’t really dug too deep into it.

You can get data from Fusion into Grafana (small example of mine below). There is a thread here and also on the Neptune forums on how to use telegraf to grab the data and store it in Influxdb. I use it for data retention and it works well.

 

[Mr31415]

I got my ReefCan 40. But this meant my Ultrasonic RO sensor no longer works. That sensor had a measuring angle of 15 degrees. For a depth of almost 50cm, that means it stopped reading a value at about 35cm - making it useless.

So I changed everything up. I am using these components:

1. DFRobot Arduino Leonardo (DFR0221)
2. DFRobot RS485 Shield (DFR0259)
3. Industrial Ultrasonic Distance Sensor with 1mm accuracy and 10 - 150cm range (URM14)
4. XL6009E1 DC-DC step up converter
5. NRF24L01 RF transmitter

Below is a (terrible) schematic-ish diagram - I had trouble finding the correct components in KiCad and I wanted to indicate how I wired it, so this is really more a wiring diagram than a schematic.

Principle of operation:

• The Leonardo uses the RS485 shield to communicate with the URM14 ultrasonic sensor.
• The system is powered via a small power supply and a USB cable connected to the micro USB port of the Leonardo - thus 5V DC
• The sensor needs at least 7V, so I had to add a DC-DC boost converter to supply 12V DC to the sensor
• To get data out of the system, I added an NRF24L01 RF transceiver. I am using this for other IoT devices in my house so this just sent data to my main controller every 30 seconds.
• Nice thing about that ultrasonic probe is that it also measures temperature so I am sending those measurements over to the controller as well.
• I have calibrated it and the Leonardo will send an alarm if the water level drops below 5cm
• I added a little feature where the LED will blink slowly when it is below 5cm, then faster until it is solid on at 2cm. This LED is underneath the tank so I can easily see it if I walk past.
• The controller will send a push notification to my phone on alarm condition, and it also logs the data to influx for grafana to display.
• Finally, I added a toggle switch to allow me to stop transmission of data for when I need to refill the reservoir and need to take out the probe, to not get spurious readings.

The sensor is IP65 rated and built like a tank. I verified the 1mm accuracy and it responds instantaneously. I also verified that with its extremely narrow beam, it can easily measure 50cm in the can without hitting the walls.

Here is a graph showing how nicely it tracks the water level (the dip on 11/08 was before I had the toggle button and I disconnected the probe for a case upgrade):

 

[n2585722]

I use a MPX2010GP pressure sensor for water level in my reservoirs. They are a bit temp sensitive but since I am only interested in approx water level in the reservoirs this is good enough. They are automatically refilled when the low sensor is triggered. Below is graphs of the sensors in the fresh salt water reservoir. below that is the input settings for the water level sensor. I also have a full and a low level float switch. The voltage input is just the voltage reading for the level sensor. It convert pressure to a voltage. That voltage is applied to a 0-10v input port.