how's that going to help with all that air exchange from outside, the dehumidifier can't dry that much air instantly.
sorry I miss read your setup. Use the dehumidifier as long as you can without raising the room temperature too high (over 85 f ). If you can open a window.
Not true, I had a tent the same size and had a dehumidifier very similar and it worked enough to drop the humidity about 15% to acceptable levels in flowering. Currently I use the same dehum. in a 8x4 tent.
That dehumidifier should be good to go but be aware that you are 2 weeks into flower, the time where that stretch is taking place and loads of growth equalling plenty of humidity from the leaves. If your levels are around 60% the dehum. should take em down to 45-50% at least. Hope that helps.