Is My Tank Too Hot?

[CrazyDiamond]

The fish don't seem to care much but it worries me just a bit. Yesterday I removed EVERYTHING from my 10 gallon divided tank and spent several hours setting up a soil and sand naturally planted tank. I was warned that rinsing my sand in hot water would heat my tank and I didn't use hot water but rather warm water. However once I had everything set up it was 88° in there O.O I thought my thermometer was malfunctioning because the water doesn't feel that warm, it feels the way it normally does when it's the desired 78° I acclimated my fish for almost 45 minutes before adding them and they were a little sluggish but they are fine now.
I haven't had my heater plugged in for a bit and today well over 24 hours later it's still 82° when will it cool off in there? My fish don't seem stressed and are acting normally, maybe slightly more active than normal and both are building nests but I notice they also rest at the bottom in the shadier areas a lot :/ is it too hot in there or are they just curious about the new substrate I wonder?

[bettacrazygirl86]

I'm wondering the same thing. Is it possible for a thermometer to malfunction? Every thermometer I've put on my far side of my tank has been reading 84-88 degrees while the side that has the heater reads 82, which is what it's set to. I've been wondering why, because there isn't anything that could possibly make that half warmer, and there also isn't anything keeping the water from circulating through the tank. Both sides of the tank feel like they're the same temperature, so I have no idea why the thermometers I put on that side are reading way higher than they should.

[CrazyDiamond]

The thermometer has never caused me grief before, I wonder if removing it from the tank caused some sort of damage, I really don't know :/ lol