T8's are not as strong as a T 5 - they are both 10's T 8 's must go inside the tank distance 6-8 inches directly above the basking decor expires in 6 months - T 5 's can go on top of screen depending on the screen - if it's a wide hole it can sit on top 8-10 inches directly above the basking decor if it's a fine mesh it will need to go inside the tank 12-15 inches directly above the basking decor expires in approx 1 yearWhich is better ? T8 or T10? I have a 10 now (22”) but I read somewhere I should have a T8.