Wish I could help but it has been a long time since I measured the temps top to bottom prior to adding the diffusers. And in the past 5 yrs, the diffusers have eliminated the thermocline. My memory kinda sucks but I think there was a 7-degree difference at the thermocline prior to adding the diffusers. I want to think the water temps have reached 91 one time in August. It is hard on the HSB and not so much on the LMB.