First time autoflower help

I am trying to grow some autoflowers for the first time. Any help would be appreciated. I have 3 Pinny Wise growing in Fox Farm Ocean Forest using Heavy 16 products, RO water ph 6.1 under Samsung lm301b QB's. 2 of the plants are looking good but one has very wispy buds even though they are the tallest.On that plant the leaves are starting to yellow. It has been 62 days since they sprouted and have been flowering for about 25 days. Any advise on when to start flush. Here are a couple photos of 2 of the Penny Wise

For soils, closer to 6.5 would be better ph. Maybe not proper nute intake is causing the fluff. To hot as well. Definitely not the lights those are nice.

I believe I might see nanners near the top on one. The lighting is not the best to really tell.

Hey man, try everything you can - check ph, check temps etc etc.
But imo - sometimes an auto will just do whatever it wants. Ive had some grow wispy fluffy buds and some grow rock hard dense buds in the same strain.

They only been flowering for 25 days. They should fill out more given some time.
but some of those colas look kinda stretchy.

things that have caused my autos to stretch in the past have been:
not enough light
too much light? Foxtailing (lights too low)

good luck. either way you should get a decent amount of bud off those plants.

Oh and when they hit the Pre Flower stretch u gotta be ready to train them Hard.
They will stretch like crazy. But i see you are already past that phase.