With the plants in flower, the opportunity for the plants to "fill in" is long passed.
The two characteristics of those plants on the left are their significant height and the significant internodal space. That indicates that the plant didn't receive much light during veg. They grew tall and skinny, reaching for the light so they didn't have much energy to grow dense foliage.
Perhaps you can get some light on the plants on the right? The ones on the left won't be yielding much.
Compare that to the photo from
@Hollatchaboy — dense inflorescence (leaves and stems) and the internodal space is much smaller which results in colas "stacking".
Another item of note is your EC/TDS. You're at almost EC 3.0. That's a lot. It might be good to figure out why you're at that level. I grow in hydro and never go over 1.6 EC. One factor might be the low water temp. At only 63°, you're in the range where temperature is inhibiting uptake of K (or P - I don't recall which one it is). At the temp, there's more DO in the water but at the expense of reducing nutrient uptake.
