Try using some screen under the MH if you can't bring the lights up higher. This will shade as much as you need (1-2-3 layers ect.) and then you can see how the BTA will react. Be carful of heat issues on the screen though, don't want you to burn down your house... never heard of this happening ,but hey, better safe then sorry. The other corals you have ( if any) will just think its overcast for a time. Shouldn't really hurt them much.