Hmm. I did not know that about hydroton; it is what I use. I do fertilize with potassium daily, with iron added 1-2 times a week.
So I guess I need a way to set up bigger, deeper grow beds.
I already failed plumbing once. (Could be two or three times, depending on how you count the various failures.) I have thought about purchasing hydroponic components and attaching them to my tank instead of a reservoir. This way, I do not drill holes that might leak.