Uneven temperatures in aquarium

[silver12]

Hello, I'm new to the aquarium hobby. I have a 29 gallon tank which I recently bought and added 5 male platies and some plants in, after using Tetra SafeStart. I'm concerned that the tank's temperature may have poor circulation. I have three thermometers, a liquid crystal one that I disregard because it seems to respond more to room temperature than tank temperature, and two glass thermometers inside the tank.

The heater is at the bottom-left, while one of the glass thermometers is at the bottom-right and says "73 F" and the other is at the top-right and says "77 F". The only source of circulation in the tank is the filter at the left side of the tank; I think it's an Aqueon Power Filter 30, but I'm not sure as it came with the Aqueon Deluxe Kit 29.

Would a 4-degree difference in the tank stress fish? My budget is low, but what should I do to improve circulation?

 

[Cactuspixie]

Are you able to add something like a bubble curtain? You could put the heater above it and that would help circulate the heat. My tanks tend to have warmer spots due to current/lighting/tank placement. I keep 2 thermometers in each tank, and so long as both stay within range I don't worry.

 

[armymp327]

i good currant would help with that (not too much depending on the fish though)

but really its because hot water rises while colder water gets pushed to the bottom, its pretty normal IMO and is present in the fishes wild habitat.