Both of the heaters are from Hydor. Except one is a mini heater. The temp. for both tanks are in their 80's now. The heaters don't have a switch at all so I'm assuming it's automatic since it says so on the instructions that the heater will change the temp. itself but I'm worried that it might go too high when I'm not around or sleeping. I'm about to go to bed so I'm really worried about this.
How warm is your air temp? These things generally raise the temp between 5F and 7F above room temp. If it's warm room that could be causing the higher temp. I have no experience with these heaters in particular. And 80F isn't exactly that bad for a betta.
Could you be more specific than "80s"? 80F is fine, 82F is fine, 84F is getting uncomfortably hot, and 86F is pushing it. Above that, you will mostly likely cook your fish. The Hydor MINI heaters don't have a shut off - they just raise the temperature based on the room temperature and volume of water. If you have a warm room and a small volume of water, they can easily overheat.
Based on the info I'm seeing here, I'd suggest taking those heaters back if possible and getting ones that automatically shut off and you can manually set the temperature. Your bettas need to be in 76-82 degree waters, and overheating can be just as bad or worse than them being too cold.
I stick with heaters that have a dial on the top and a temperature reading on the front so you can set it yourself with the dial. One with an "on" light is also helpful so you know when iot's heating ro not. Also, I keep the thermometers on the tanks so I can watch the temperature and regulate if needed.
You can get one of those you stick on the outside of the tank to make sure you're not hurting your fish. It's a cheap way to keep an eye on the temperature.
I have the Hydor Mini and i wish i didnt get it. I do keep my apartment around 60 so the tank isnt at risk of overheating but i just got lucky there. without anyway to control the heat it produces its gonna be risky in homes that at 70 degrees +
The hydor slim heater is doing a good job at keeping the temperature at 80F but the mini heater kept bringing the temperature higher and higher so I unplugged it. Really? on this forum it said that 86F was fine for them.
There are illnesses that can be treated at 86, or some places have really hot summers, and bettas tolerate it. I've heard that 79-82 is ideal. The bigger problem is that if your heater is bringing the temp up to 86, it may not stop there... and higher than 86 is not fine.
What size tank is the mini heater in? I noticed that the hydor mini was powerful enough to keep my one gallon tanks (that are 64 degrees without a heater) at 76 degrees. I stick with Hydor because my landlord keeps my apartment complex at the lowest healthy temperature possible for the tenants. So I need a heater that doesn't take prisoners. XD
If you have your fish tanks in a room that is around 70 degrees and the tank is 1 gallon or less a hydor mini can potentially overheat the water. : /