I think your plants have good genetics to begin with, and I would not be so ahead of the game by wondering how much I am going to yield. Use your time and energy for the now, and do the best you can do for your plants at the stage they are at, and you will find out after you harvest, dry, then cure your plants how much your plants, in your system will produce...Lookin good so far....

What size light do you have, how many plants, are you using a bloom enhancer? What ppm are you @, PH, and temp in your room? Do you have a air cooled reflector? You are getting good bud growth for the 4th week of bloom, it is time for max PPM, and a good bloom enhancer and they are going to explode! Remember, sativa's take longer to finish, so I think they are off to a great start...

is this your current grow? or previous?... i'm interested to see what your total yield is off the plant

This is my current grow and over the next 28 days or so i expect them to swell to way over the fatness of a can of deodorant,hopefully,the tops are almost as fat as a can of deo now so hopefully they will swell to twice the fatness by harvest time,also with my watering and potting techniques i hope for them to be very resinous.
The thing i noticed with over watered bud in big pots is that it tends to stretch and produce big fluffy buds that look cool until they dry up and only weigh 10 grams,when the buds are very oily and tight they weigh a lot more.

The reason i think that plants make fluffy bud is because in dry conditions the plants need to retain moisture so they make lots of oil and tight nuggets so they cannot be so easily dried by the sun because of their tight concentration in the bud formation and the wind cannot move through the buds very easily because of the larger amounts of oil and extra tightness of the buds and in wet conditions they need to lose water they do this by stretching up nearer to the sun and because the wind moves through fluffy buds a lot easier and helps the plant to exasperate excess water,so windy,not to hot but hot and dry conditions yet still making sure you keep her just healthy and your buds will weigh a lot more

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I have a 400 watt hps HTG light setup , with vent in and out of the room, im using bloom burst 10-52-10 with six plants, i do not have a Co2 injection system, the PH is at around 7.0 and the temp is at around 77 to 82 degrees F.