Yeah it's just a pH/ppm/temp sensor. I love it, but it's all I've ever used so I can't compare it to anything else.
I liked it enough that I bought a second one to monitor my top-off resevoir as well. Might be a little overkill but I like to use this chart...
View attachment 112868
...and, from my understanding, this chart only really works if the top-off is the same as the lower resevoirs.
I'm sure it's not totally necessary, but bluelabs are top tier.
One of the two has wifi capabilities, but I've never used that feature. I only bought the wifi one because I found it on sale cheaper than the standard version.
So far, I've replaced one probe because it seemed to be "growing" some shit on it. Bought the new probe when I bought the second monitor. The other probes have since accumulated the same gunk, but they calibrate fine and continue to read accurately. The extra probe was likely unnecessary.
Hope that helps. If you're diligent, you could get by using their pens for quite a bit cheaper. I just like to look in my room and see where the water sits. I try to avoid as much work as possible.
Edit: I looked them up... I don't remember spending that much. They maybe have gone up significantly. The probe I remember spending $69 on is now $82 on my "buy it again" page on Amazon.
what
I would would check reviews. Google some other brands and at the end add the word reddit. Like "bluelab gaurdian reddit". You'll find some decent reviews with tons of feedback and discussions. Side note: that works for everything. Reddit is the shit for customer reviews.
They're sweet... but I don't know if they're $340 sweet. That's the 3rd gen, though. I'm pretty sure mine are 2nd gen.