I've never bothered with digital. I use the suction cup glass type myself. Of course, a stick-on thermometer is going to be a better choice for something like a big cichlid that could break a glass one or try to eat a digital probe. I learned this lesson after my brother-in-law's Texas cichlid pulled a really expensive digital instrument (temp, pH, TDS and maybe some other measures) into the tank by yanking really hard on the probe.
I had a digital and it sucked. My oscar was always chewing on the wire so maybe because it was always moving around but the temp would vary wildly. I assumed it was the heater going bad and then the batteries died so I dropped in a floating one that was supposed to have a suction cup but it just floated free and lo and behold, the temp was perfect and never fluctuated. The next time I ordered from fostersmith I bought three or four of the bargain suction cup ones. You just can't beat mercury.
Sounds like i will be sticking with the glass suction cup type after all. I figured the digital would be a nice upgrade. Thanks a lot guys. I'll just buy a handfull of them and hope they're more accurate this time.
I just bought a new 20 gal Aqueon deluxe kit (newbie here) and it says it comes with a "digital thermometer" and I got excited. Turns out that just means one of those stickers that goes on the outside.
After reading this thread, I think I should go buy a submersible one, but after iamntbatman's story, I don't know what I should do.
if you stick with a floating type WITHOUT the suction cup it is alot harder for any large fish to break them.........They work the same, but with the suction cup keeps the thermo right next to your tank and allows fish to keep banging it against the side...........with a floating type the fish will just knock it around your tank and eventually lose interest.......