I really need some advice please. I am a newbie when it comes to owning a tortoise and have had my 1 and a half year old hermanns for about two months now. I thought I’d done as much research as I could before getting him/her but it turns out I’m stumped. 

I got her with her 4 foot enclosure and combined uvb/heat light. The previous owner told me they had had the same bulb from getting the tortoise in may 2019. From what I had read the bulbs are only good for about 6 months before they stop giving out the correct uvb rays so I purchased a new bulb...... the previous temperature under the basking light sat at about 30 in the basking area and 20 at the cool end. 

Since getting this new bulb the basking area is 40 degrees. I am worried my little pebbles will get shell  burn or some other horrible thing from this. I purchased a pulse thermostat only to read they were no good with heat lamps, then I got a dimming thermostat but again no luck as it’s a Mercury vapour light. 

I’m really stumped as to what I can do next short of changing the whole set up and having separate lights. 

I would really appreciate any help or advice if there’s a possible way to control the temperature of this light or if I need a new one. 

Thank you 

Gina