FWIW.. I had a nice long chat with Pankaj part of their tech support last night. He went into a lot of detail about how the product works and what the problem might be on my end. They have all of the "raw" data from my device on their end and he was able to pull up exactly how many times my system had failed to take a reading, and how many times I have asked it to do a manual test, etc. Here's a little of what I learned.
I think everyone knows this but the water guru sense is just a submersable digital test pad reader. It uses the cassette to present their proprietary test pads to a digital reader in the sensor where it shines a light on the pad and takes a digital reading. The cassettes contain 3 types of pads. A calibration pad, a FC pad and a PH pad. When taking a reading it first shines its light on the calibration pad and since it knows that's supposed to be white, it uses uses the results of that to adjust how it interprets the color of the other FC and PH pads. Once calibrated, it will then present the FC and PH pads to the reader shine a light on and take readings of. The readings on the calibration pad have to be within a certain range, however, for the devices software to believe it can successfully interpret the FC anf PH readings. If the calibration pad reading step isn't within that range the device will give up and not take the FC and PH readings (for that day), and that's apparently what has been happening on my device. Every time this happens the cassette uses one calibration pad, but does not use a PH or FC pad.
Different pool chemistry apparently affects the readings which is why they need to calibrate each time they test. In theory, since the pool chemistry of your pool doesn't change "that much" day to day the post processing software on their end is able to use the historical calibration readings to improve their current test results. I think I may have noticed this on my end, but I'm not sure since I still get some unsually large swings in FC and PH day to day. Some back information about the cassettes is that they protect the pads between thin layers of glass, and there's 58 pads per cassette (o the device can have failed readings and you'll still get the promised 6 weeks of readings from the cassette). The current generation of cassettes don't have the technology to report how many pads have been used and are left, but that is supposedly something that will be added to future versions. What is reported in their software is merely a count down of the number of days since you changed the cassette though. The limitation on the cassettes is that the chlorine in the pool eventually affects and infiltrates them and that's why they have only a 6 week supply in them. But if you keep cassettes in their sealed container that they ship them to you in, they should last a long time though (definitely across one season to the next.. so an unused cassette from this year can be used next year)
Based on the information on their end, they believe that both the sensor itself and the cassette are working properly on my end but that tiny amounts of dirt, or possibly bubbles have been disrupting the reading. It's an optical process that shines the light to the sensor so small amounts of dirt, or even bubbles can interfere with the reading. They didn't say this, but I believe this is why the "net" to wrap the device was added and I'm guessing it was probably added as an afterthought to try and limit how much dirt the device is directly exposed too, but I don't really know that for sure. Dirt is dirt, and that can often be cleaned by removing and reseating the cassette, though they say you shouldn't have to do that routinely or repeatedly. He also said that warmer water has more oxygen bubbles in it, and those bubbles can also sometimes interfere with the readings.
At the moment, of course, my device is working fine. It skipped two readings earlier this week. On the one day, asking for a manual test didn't do anything, and I got no reading for that day. On the other day it did finally take a reading after manually asking it to do so twice. Even though i haven't touched it, it's since worked fine for the last 3 days. They say all of the readings and numbers on their end look good for the last few days. Just in case, they're sending me another cassette (mainly because my current cassette doesn't really catch when you insert it) and we'll see if that makes any difference in terms of reliability.
I'm still a little on the fence about this device and am still considering sending it back if it can't be made to test reliably. I'm coming to the end of my 45 day return policy. They say they'll extend that since I'm working with them to see if we can pin down and fix the issues. I'm taking their word on that, so hopefully that won't come back and haunt me.
When I first talked to Pankaj he was off getting tested for COVID, since I think someone else in the company tested positive. He's concerned that they may get shut down again because of the pandemic, and that might affect me getting the new cassette and/or any ability to reach them and get responses from them.
I'll let you all know how we get on.
