That is a nice collection of crypts you have going there, Phil.
Get someone to drill holes on the bottom of the tank and centralize it to a sump tank.
Easier to change, fertilize, heat, and circulate the water.
I have always wonder about the humidity requirement. My L. inclinata is growing out of the water in my indoor experiment. It is an open system. The lighting is low at 2x 15 watt over 22 by 22 by 5 tub.
Have you ever try growing the crypts with part of the lid open or no lid at all?