My plan is to only flood up to about 2" below the top of the hydroton. As far as the hydroton blocking the siphon, there are a number of ways to prevent that. The easiest is a simple guard around the siphon with holes or slots cut in it that are smaller than the hydroton. The guard will be open at the top and extend up through the hydroton, so I can check it periodically to see if roots have gotten inside, clean it out, etc.
As I said before, these automatic siphons have been in wide spread use in general hydroponics applications, all over the world, since the early 1900's at least. That includes large scale commercial hydro growers. Those guys dont want to mess with dozens of timers scattered all over a huge hydro farm and the increased failure potential. Most of them recommend them because they are simpler and more reliable than timers. A typical setup would be either a long row of individual tanks with a single auto siphon controlling them all or a single siphon on a large table or row of tables.
Your point about my continuous cycling being too much flood time was a concern of mine from early on.
Ive thought about that a lot, and I
think that, if you look at a waterfarm, or DWC or RDWC, or even a hempy bucket, a large portion of the roots are sitting in water 24/7. That makes me think that constant cycling 24/7 would not be a problem. As I understand it, the main advantage to an ebb/flow setup, over those others, is that fresh air is being drawn in over the roots on every cycle. It seems to me that more cycles would be better. The other advantage of faster cycle times would be a more constant temp inside the root zone. If it sits a long time with no water, the temps will tend to climb due to heat migrating in from the grow room and your media and roots will warm up - only to be shocked by the cold water entering on the next flood cycle.
Or - is my thinking way off on this?
I will for sure keep you guys up-dated on how well or poorly this works