The top drip, gravity drain you set up for your mom's looks great Hellraizer. Simple and effective. The feed and drain lines empty so there is nothing in the lines to heat up. The roots get optimum air from the nutrient solution and when drained. They can be feed more often, then a typical flood and drain. What's your timer set at for feeding?
I'm not trying to stir the pot here, but why under current ? The grommets on a ebb-n-flow would be the first thing I would get rid of. To much of a chance to pump your hole rezz out on the floor. Now add larger pipes, bigger grommets, more water and larger pumps ! To me thats just asking for problems.
Don't get my wrong, I have nothing but respect for anyone that can build whatever they put there mind too !!
But sometimes the simplest methods seem to be overlooked for something more complicated. (gravity always has the same effect)
MYWhat?