I think this is a question I've answered 1000 times..the same way.
and to start with, no one has to do it the same way as I or Purp does it.
Some growers on this thread have a DIY, and not even a true SH Bubbleponics with different size hubs and water pumps..
And just because two growers does it different, doesn't make one right and one wrong.
My nephew PurpDaddy, whom I am very proud of, gets great results, WONDERFUL RESULTS, he grows beautiful buds, and he definitely uses different Nutes, different supplements, different catalysts, different Lights, different strains, different Veg times, different water source, than I use. And he perfers Michalob Beer, and I drink Miller Lite, and we both get high.
You don't have to do it the exact same way as Purp or I do it.
That being said first,
what I do and think is best for ME, is when my roots are well into the deep water at the soonest, or when I start flowering 12/12 at the latest, I unplug my water pump. Within the first 3 to 5 weeks, I always find a clogged tube, ALWAYS, clogged with a root in it. AND that root will die too, messing up pH, and everything.
I will remove that clogged tube, you can not unclog it while it is IN the tank. Sometimes, if I can, when I remove males, I will remove the hub, and sometimes I can't remove it without doing a lot of damage to the roots. Sometimes I remove a few tubes and leave a few until i am removing males. No matter what, I have never Removed the pump. I always use that pump to drain my tank, and I let it run some, shooting water staright up against the lid. It cools the water, it moves the water and moving water is much cooler than standing water.
If you have ALL the roots in the deep water, then those feeder tubes are like big breasts on a nun. They might look good, but there is not much purpose to them. IF I get a clogged tube after the 3rd week, I just unplug the pump, and see if I think I can deal with it, fix it or not.
I do keep the feeder tubes running to the root base and the water pump pumping as long as I can, but I've never been able to do that more than 4 or 5 weeks at the very most. Normally it is at about 3 weeks. And I have kept them running all the way up to the first day of 12/12. Most times, although I unplug the water pump, I wait until I am removing males, to remove the hub and tubes then, since I am going to be wacking roots off anyway. And I have left some tubes to save some big roots from being torn in the process.
I think I might try some WATER PUMP FILTER BAGS.
I am even trying to get Martin to make them, or pay me to make some. Use Window Screen, to make a small draw-string filter bag, that I put my water pump in. That way, I could leave my feeder tubes working longer. I only remove them because they get clogged with a root, and let roots die. i think it would be better, but not necesary, but might be better to keep them feeding the root base and circulating the water around.
You can not go wrong, doing like PurpDaddy does, for sure. He has taught me a lot about growing, for sure.