Lowryder questions. (week 6 of grow)

I'm in week six of my lowryders life, and it has kicked off flowering. I have kept it on a 24/7 light cycle because its autoflower. I have read in a various places that it might be a good idea to go 18/6 during flowering to increase the yield, would that be a good idea?

Also, I have been using IONIC Grow, and IONIC bloom for my nutrient soloution (I'm growing via Deep Water Culture). I used Grow for the first 5 weeks, and I have just changed to bloom. My question is, might it be a good idea to combine the two (grow & bloom)... or just stick to bloom by itself for the final three weeks?