
Originally Posted by
Megalodon
No, you only need to purchase reagents and the test tubes (if you buy used and they're not included).
The previous generation had 3 models: the 820, 850 and 890 which I believe tested 20, 50, and 90 parameters respectively. The 890 has 4 LED wavelengths so I'm assuming the 850 has 3 and the 820 has 2. You need the 890 if you want to use the improved nitrate test method though.
The next generation only has one model, the 900 which is exactly the same as the 890 but adds a backlight, USB, a better menu, better drop resistance, and data logging.
Shortages have doubled the price of the 890 on eBay and some used 900s have been going for close to MSRP. I still think it's worth it though.