Take em all the way to 24/0. I've had plants take a couple months to re-veg even under that. Hit them with a shot of superthrive at a couple drops per gallon of food. The other reason plants just keep on flowering is the AGE of the cut (the from-seed age) but in your case I highly doubt that plays into it. My OGKush 'abusive' throws significant pistils under 24h light- since I store males in the same closet, I get OGK x ??? crosses making fully healthy seeds on the regular. haha ask Chron, he's about to yank some nice seeds off his OGK!
But try 24h light and superthrive.
Men make their own luck. Children accept the luck that life throws at them. -Stinkyattic
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You can lead a horticulture... but you can't make her think. -Rhizome