How much longer flowering?

Hey guys. I'm 7 1/2 weeks into flowering with this pure landrace sativa Durban Poison, and I'm wondering if anyone might be able to tell how much more time this plant may need. It's under a 450 watt LED grow light, with two 100 watt supplemental lights. It's being grown hydroponically.

Sativas tend take quite a but like her to flower than indicas and hybrids. 11 or 12 weeks of flower is probably a safe bet for minimum flower time with Sativas. Some go even longer than that. Keep your eyes on the pistils and trichomes for clues to maturity.

buy a scope off amazon for 11 bucks... when the trichomes are turning amber thats when you chop em... it looks like you have a few more weeks..girls look beautiful btw! nice grow!

If you are able to observe the resin glands degrade then harvest when it's at peak healthy full trichomes, with maybe 10 percent of them being degraded.

Otherwise what I'd do is what's the swelling of the bracts each day, and when 70 percent of the pistils have turned brown from age, harvest.

As above probably 3 to 4 weeks left, they are still growing look at all them lovely pistils still bright white!
Looking real nice though man gonna be a killer harvest.

I just bought a usb scope of fleabay for about £10 and if you have an android phone and a mini usb to normal usb adapter it plugs right into my phone so i can take snaps of my bud without moving or cutting bits off.

Few pics of purple haze about 2 weeks before harvest