Temperature drop?

[labpig]

I have an 80L tank with neon tetra, Otto, coral platty, 5 banded barbs and a betta

It's been running about 4 months and has always been at 25.7C
yesterday I took out the spare filter from my old tank that I used to seed this tank. I also rearranged the artificial plants

The temp has dropped to 24.8C. I haven't touched the heater. I have a juwel filter where the heater is in the same housing as the filter

1. Can the temp drop because there's less resistance through the filter and the water is circulating faster? What else would cause the sudden drop?

2. Is this new temp ok for the fish I have? They actually seem more lively. I'm not sure if it's because there's more free space to swim or because of the temp

Thanks !

 

[Delapool]

It sounds odd but if that is the only thing you have changed. The degree difference should be fine.