I'm on the other side of the US. If I left my tank by the window, it would be over 105 degrees by lunchtime. Back in July when I noticed my betta acting weird clinging onto the side of the plastic log, it was because his tank was 95 or 97 degrees. It was day 2 of a 3 day heatwave. Lucky I noticed him & had 4 thermometers on me, or I would have lost everyone.
Now I use a digital thermometer that gives me a reading within 1-2 seconds. I usually keep the good ones in the kitchen.
The filter with the broken intake? What brand & model was it? I have a lot of used filters that have damaged intakes, but that's what a prefilter is designed for. I have to pick up materials to make some.
The fluval black sponge prefilter that my friend recommended is too small.
Right now, I'm watching my halfmoon betta is in my 6G guppy tank.
He's been out of shape for the past couple months & I have AquaClear 150 running in the tank.
Rated for aquariums up to 30 gallons
He was hanging out right by the intake & also hanging out directly where the water shoots out from above.
I just turned it up to max power, so he gets more exercise. I'll turn it down after I do the clean the bottom of the tank and replace the ornaments.
He's swims like a fat penguin now.
Sorry to hear about your 6 fish. Did you have heaters in the tanks that overheated?