87 is WAAAAAYYYYY to high. 80 to 85 day time. 75 to 79 night. Try a larger heating pad for a 10 gallon tank too. It should compensate for the lesser light bulb.
87 is the hot side nd today it was 70 degrees outside during the night I switch to my 75 Watt moonlight bulb nd just leave the pad on keeps it at about 70 75 degrees