Hey Grump, have not been around as much as I would like lately, but I'm really impressed with what you have so far. I see a very nice harvest in your future. Lots of bud sites spread out nicely.
Since this is your first real grow with this system, I would recommend not pushing it. You could probably get more bud with more photons, but that introduces other things to consider. If you push them, you have to have things dialed in (which you do) but it will change the environmental and water requirements, and I vote keep it on the fairway this time. Experience is the best teacher.
Silica by itself is something that will not improve bud structure. Also, the potassium it adds may push you off the fairway in terms of nute % in the res. So I agree, you are in the timeframe to back that down.
I'm pretty sure you are using GH PH up. This is what is in that:
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The carbonate is what is the active thing here. But as the carbonate is used to buffer PH, you are left with Potassium. Plant ready potassium. So that is a factor as well.
If you have to add lots of PH up to keep things stable, it can impact nutrient ratios. The problem with using GH Flower is the ratio of P to K you can add (or remove) is fixed. It comes out of the same bottle.
So this is a warning that if you need to constantly add PH up in excessive amounts, you have something going on in the root zone, and you will need to dump your res weekly to keep your ratios in the right range. Hope that makes sense.
Anyhow, you are doing great and should be proud of yourself. Shout out to all the pros that contributed I think you are getting great advice. It is obviously working.