I think promix has some fert in it and I know for that FF ocean forest does too. I think you've over done it on the ferts, the bloom in particular. I think your leaves are yellowing because of high phosphorus which is poisoning them. You don't need to fert so much in soil, especially if your soil has fert in it already. You could probably just use FF for an entire grow after the plants are about 10 inches tall without ferting, because that's what it's made for. The light warrior soil is made for small plants. They grow up some, then you transplant into ocean forest and just give water. People are always adding more fert to ocean forest but the reason why you buy this soil to begin with is because it has fert in it. If you search the web, you'll see words on ocean forest that say: "Ocean forest organic soil is ready to use right out of the bag," and this: "Ocean forest organic potting soil possesses everything in one bag." It doesn't say add more fertilizer." You see what I mean?
Diluting with promix might be a good idea, but adding so much fert later probably isn't a good idea. We see a lot of this, where growers keep adding more fert to FF soil because they're under the impression that this needs to be done, but it just isn't the case. So for these plants, I would just water when the soil is dry until you get a small amount of runoff and let it be and see how things go. Maybe consider transplanting if you want, but at 3 weeks flower, you seem to have more than enough fert in the soil now. It's easy to confuse yellowing leaves with a lack of nurtrients, but over ferting will cause the same thing - as the leaves die, they turn yellow.