Red bulbs are better - the blue ones are dim and seem to give off a light that amphibs can detect. ..I hate them!

The red do give off a lot of heat though so ideally you need to mount it outside the tank.

Chubby frogs are quite tolerant of temperature but like most anurans excessive heat can quickly prove fatal...so I would suggest starting with either just the heatmat or light - mine drop to around 20c during the night.

Also I would suggest mounting the heatmat on the side of tank rather than below (sorry if you've already done this - I can't see your pics) as they will burrow to keep cool!

Hope this helps

Steve