Digital Dissolved Oxygen Meter, GIDIGI Dissolved Oxygen Tester with ATC, DO Meter with 9.84ft DO Probe Cable, Dissolved Oxygen Test Kit for Aquarium, Ponds, Fish Tank Range 0.0‑40.0 Mg/L

Use very often!

Once i plugged it together it will not come apart and pulling harder to try and get it apart only makes it's reading go crazy don't buy this.

The app doesn't work.

Funciona bien, solo hay que calibrarlo la primera vez y ya se puede usar sin problemas

Edit: Seller reached out to me direct and provided an instruction manual and answered some questions. Will not connect to Bluetooth on Samsung Galaxy S24. No instructions other than "Connect to our app!" No calibration instructions, just garbage pictures on the store listing that leave you to guess what exactly is supposed to happen. Temperature probe reading is ~2°F higher than other probes. I haven't decided if I'm going to return it yet or not... I'm going to try more research and troubleshooting before I give up on it...but so far, I'm not impressed.

I got this meter to read the dissolved oxygen levels in my many fish tanks. They are all planted and should not have any issues with oxygen, but I had one tank that could not support even a few shrimp. After all of the basic parameters checked out I decided I should find a way to determine the amount of the oxygen in the tank. Reduced oxygen could indicate a chemical issue with the tank or a bacterial infection, or insufficient filtration, among other things. This meter comes with well-written and easily-understood directions. There are a few grammatical issues, but the manual was presumably written by someone who doesn't speak english as a first language, and considering this, it's well done indeed. If you follow the instructions laid out in the book the meter works exactly as intended. It is crucial that you perform both the zero and slope calibrations prior to using the device or the obtained readings will be meaningless. I found the meter to be accurate, especially when using the conversion chart for temperature that's in the book. When used qualitatively you can see if there are glaring issues with the oxygen levels in your tanks. I'm not using it to split hairs, a percent difference here and there isn't what I'm concerned about, so now that I trust the device I'll only be using the correction factors to spot check the meter. The probe has to be filled with electrolyte to work and is sensitive to damage and drying out, so this meter requires maintenance that standard pH and salinity meters don't. It comes with spare probes and spare electrolyte so when the probes ultimately are consumed you have plenty of spares to keep it going. You can also order replacements when needed. All in all this meter does what I want it to do and is relatively simple to use and maintain. If you have a need to measure the dissolved oxygen in an aquatic sample, this meter represents good value.

Too complicated. You almost have to be a degree scientist to use this thing. I question the accuracy of it as well.

I got this because there was a major algae bloom in my saltwater tank, my ORP was dropping, and I was worried that oxygenation might be impacted. I was able to follow the steps, link the advertised iPhone app, and check a sample from my tank and verify that oxygen levels while not perfect were in the lower end of what should be considered normal. Two weeks later my fish and tank are still doing fine. I will say this device is complicated to use. The first time you use it you must calibrate it using zero oxygen water and must do it quickly after opening (within hours) or the calibration fluid will spoil leaving you unable to use the device unless you can acquire more. This is not unusual for any Science based instrument though and should be expected. If you have a device that requires no calibration you should be skeptical of its efficacy at least with today's technology. Once you've done the first calibration though it is fairly easy to use it again later as you only need to calibrate against the air. Just remember (and this part could probably be improved upon) you need to reset the parameters in the app and set them again after the calibration.