RCYAGOSmart Bluetooth Dissolved Oxygen Meter

The meter is easy to use, and the included instructions are thorough. The 5th photo refers to it as a PH meter, but the meter does not measure PH, only dissolved oxygen (DO) in both % and mg/l, and temp in both F and C.The left (up) button holds the measurement, and when held down, changes the temp units from C to F. The right (down) button changes the DO units from mg/l to %. When held, it puts the unit in calibrate mode. The power button, when held down, turns on the bluetooth function to connect to the app.The app was easily found via the QR code in the directions. Once installed, it requested location data and bluetooth access. I allowed bluetooth access, and when I put the meter in bluetooth mode (held down the power button), the meter connected immediately.The app is easy to use and allows additional functions to set altitude and salinity (which affect DO measurement), save the readings (auto save or manual), and turn on/off the backlight. You can 'share' the data which puts it in a .xlsx spreadsheet attachment to email/text/etc, according to your phones functions. The spreadsheet is formatted for several columns of other readings (TDS/PH/salinity/etc) which would appear to be for compatibility with other meters by the same manufacturer. You can also enter notes for each reading through the app.The probe requires an electrolyte solution, and includes instructions on how to clean and replace the solution. A bottle is included, along with 6 replacement probe/membrane covers. The probe comes with a membrane and solution already installed, which wasn't clear, so be careful when unscrewing the probe cover.Batteries (3x LR44/357 button cells) are replaced through a screw-on top cover which includes a rubber o-ring.The only drawback I found is that the backlight can only be turned on through the app. The display is a standard LCD display, it would be nice be able to turn on/off the backlight through a button (or by holding a button) on the meter itself.

The instructions are horribly unclear and misleading.It says "Unscrew the membrane, replace the electrolye. Then screw on the membrane." I believe I've interpreted what it's asking for is this:Unscrew the membrane: Have to find the very small diagram at the end of the instruction manual, and that explains what the "membrane" is. Take this all the way off.Replace the electrolye: What the mean is you take the bottle that says "Electrolyte Fill Solution" and you just fill that cup-shaped "membrane" with contents of the bottle. Make sure you have the right orientation with the clear end on bottom .I think this is why this little component is called a "membrane," because I believe that's what this clear end really is. You don't need to fill it literally to the top, because when you screw it back on, the little electrode deal is going to displace some of the solution.Screw on the membrane: You need to continue to maintain the membrane component with the clear end down, so that you don't spill out the solution. Recommend having a tissue or paper towel underneath this activity. Screw the probe and the membrane together, and make sure it's tight.I believe I've read on here that this membrane should come out of the box with solution loaded in already, but that was not the case for me. When checking the state of the solution inside, be careful that you have the right orientation, so you don't spill it everywhere.Also, the instructions mention the 100% calibration point and the 0.0% calibration point. For 100%, you're just going to measure the air, but for the zero point, it just says "Put electrode into the zero oxygen water." So I've done some research, and it seems that in order to perform this calibration, you have to obtain some sodium sulfite (Na2SO3) in order to make up a solution that would contain zero dissolved oxygen. There's no mention of the need for this anywhere on the seller page, in the instructional videos, in the instruction manual, or on the mobile app. They could have opted to include some amount of this needed reagent, but chose not to, for what reason I can't imagine. This zero oxygen water solution is (from what I've researched so far) not possible to make up from household chemicals. I considered trying concoct one, but am not sure how I might damage the membrane in doing so. So unless you want to go buy some specialty chemicals on the side and make up your own solution, then you'll end up just using the 100% calibration point. It's not explained how impactful this is to the effectiveness of the calibration. To be conservative, I'm assuming that it is severely impactful, and am probably just going to return this thing, since I'll never fully trust what it's telling me.

Calibration was a challenge and there wasn't much online to assist. I was finally able to configure it with my iphone and feel pretty confident it was measuring well. For $100 instrument it was worth the investment. I am using this device to measure DO in my 2.5 acre farm pond. Readings were 8.2 - 10.7 % DO and temp was measuring around 70 deg. F. I am pleased with my purchase.

First, the instructions are vague and incomplete. There is no guidance on when to replace electrolyte or membrane and whether to replace both at the same time. There is no information about refills, either. The device purports to give pH readings but there was no mention of that feature in the instructions at all. The bluetooth connection failed unexpectedly. The readings I did get on both pH and dissolved oxygen were wildly inaccurate and inconsistent, eg. pH 14.0. There was no support from the manufacturer. The product appeared to be a great concept, but it is not ready for the market.

This is a dissolved oxygen meter with logging facility. The device consists of a display unit, a sensor unit, and a 42” cable to connect the 2 parts. Also included in the box are 6 membranes, a 30 ml bottle of electrolyte solution for calibration, and a paper instruction sheet. The device is powered by 3 LR44 (button) batteries (included). The device measures dissolved oxygen and temperature. Using these 2 measurements, it calculates % oxygen. In addition to readouts on the screen, you can download the YINMIK app, which will log your readings via Bluetooth. Data can be exported from the YINMIK app or printed.I really like the way this oxygen meter has Bluetooth logging, so I don’t need to write down values in the field as I take measurements. The accuracy seems pretty good, at least for my purposes, understanding stream morphology and macroinvertebrate abundance. The device is relatively easy to use, and great for basic purposes.