OHF pump raising tank temperature

[sword28]

I just set up a new tank using OHF, my first time using OHF.
I have a problem now, i.e. high tank temperature.
Tank temp without glass cover = avg bet 30.5 to 31
Tank temp with glass cover = avg bet 31.5 to 32

I can only suspect it is the OHF pump submerged inside the tank to pump water to OHF, because the ambient temp is around 28 to 29, can't possibly the tank water temp can be higher than ambient temp right?
Tank is in living room with ceiling fan on most of the time so tank area can be considered quite well ventilated.
Another reason why I know it is not ambient temp is, even with living room air con on for few hours, tank temp did not drop much.

My setup :
Tank = 3x2x2.5H, 12mm thickness
OHF = 3 tiers (6 boxes)
Pump = Eheim Compact 3000
No light on because still cycling tank.

Question:
1. is it normal for tank temp to go until above 30? I talked to few LFS owners and most of them commented that it is unavoidable that OHF pump will heat up the water, so no point changing pump. Somemore eheim is already considered as one of the better pumps, MIC ones may generate more heat.

2. Does anyone having similar setup and problem? how you resolve it? I know I can use fan to lower the temp, but I hate to top up water often for the faster evaporation.

3. Or is there really a pump that will generate less heat? please recommend.

4. Intend to keep altum angels and some plecos, possible with 30 to 31 temp?

[tetrakid]

The submerged pump is effectively water cooled, so the heat generated by the hardworking motor is absorbed by the water.
The best is to leave the tank uncovered, or use netting material for the cover.

[tetrakid]

You can also customize an aluminium heat sink at the backdrop of the tank