So, peeps, a wee story of one good idea, one screwup, and how the good idea saved the day.
The Good Idea:
I lined the bottom four inches of my 4x4 with a couple layers of 6 mil poly. The thinking being that I I had a timer or pump failure that left the pump on, the poly would contain the entire reservoir of liquid, avoiding a flood.
The Screwup:
My reservoir setup allows me to mix nutes with my pump. I close the valve to the 'Drobe, open the valve that just recirculates output back into the reservoir, and move plug the pump directly into power to turn in on continuously while I do the nutes. Aeration and mixing. So, this morning, I mixed up some nutes before going skiing for the day. Once the nutes were mixed to EC and pH'ed, I moved the pump plug back to the timer outlet after putting the valves back in irrigation mode. The only problem was that I grabbed the wrong black plug and moved it to the timer, and left the pump plug running.
The results:
Got back from skiing, went to the drobe to check things, found the pump running dry in the reservoir, and about two inches of nutes in the containment. So, the poly liner did its job, no flood.
Sadly, the jury is out on the pump. It has oil in it, and there was oil in the empty reservoir, so either the pump spewed oil past a seal due to air pressure when the pump heated up, or the shaft seal is buggered, and the pump is toast. Dunno which yet.
So, the liner saved me from a flood, but my grabbing the wrong black plug and moving it to the timer may have cost me a pump. Good thing the grow is nearly done.