Dissolved Oxygen Meter with Bluetooth Filling Fluid Range:0-30mg/L, with Automatic Temperature Compensation Function,Pen Type Dissolved Oxygen Test Kit for Aquarium, Ponds, Aquaculture

I ordered this meter to use on my planted aquariums that have CO2 injection. Nothing is scarier than seeing your fish floating at the top of the tank! With this meter, I was able to monitor the DO levels in my tanks to ensure that there was enough oxygen for my fish to survive. The device is easy to use and there really isn't much to it. I recommend it to anyone with planted aquariums who are looking to add CO2 or even if you already have CO2 and just want to monitor the DO levels. The batteries are annoying because who actually keeps a bunch of the little button cells around but other than that, it's not a bad tool to keep on hand. The price seems high but it's really not, especially if you compare that to a tank full of dead fish.

I got this to use with the various water sources (irrigation reservoirs, fish tanks, ect) that I have here at home. The overall operation is relatively simple, and it even has an app if you want to do data logging or whatever. I'm probably not going to use the app, as all I do is stick it in the water to check. But if you have more advanced needs in terms of data logging, the option is certainly available here.It even comes with a nice supply of electrolyte solution (aqueous potassium chloride - utterly harmless, you can drink it if you really want to, it's extremely salty, like drinking salt water, and is in fact also a common salt substitute for food called "No Salt").When you fill the probe cover with electrolyte solution, slightly (by a few drops) over-fill it so when you close it up, a slight amount of solution squirts out. And before you close it, flick / tap it gently with your finger to shake any bubbles out of the solution. Bubbles in the solution WILL affect the accuracy, so you want there to be 0 bubbles when you close it up.My only complaints are, 1, there's no carry case. I mean, you can keep it in the original box I suppose, but something a bit more...compact and appropriate...for long term storage would have been appreciated. And 2, it's powered by stupid button-cell batteries. It really is high time for the water tester industry to wake up to the fact lithium ion rechargeable batteries exist now, and it's SO much nicer when it's rechargeable. There nothing worse to find your batteries dead when you need your meter, or worse, have gone dead and leaked, ruining your meter completely.Overall, it's a fantastic meter, and works really well. One day, *fingers crossed*, they'll start to make them rechargeable.