Your plants look great. Trainwreck is relatively easy to grow. I have never really had any deficiencies with them with a basic proper nutrient formulas like I run into with other plants. They can take and thrive in a high EC nutrient program.
However as someone that has grown a lot of it (it is one I grow at least once a year) it is not easy to control in flower. I primary grow the version from Green House Seeds. They will at least double if not triple in size during flower. I have flipped them at 14-16" and had them finish over 5ft indoors with LST in a DWC medium. In Coco they are more somewhat more manageable. I have never grown them in soil.
Adding silca isn't going to change the genetics in the plant. It is known to be a viny fast growing and borderline out of control plant. Adding lots of varying air movement will help strengthen the stems.
You are going to need trellis netting, stakes or a ton of yo-yo's to hold them up when the buds start to get heavy. Typically they grow heavy spear shaped tops on the main stems and gold ball nugs all over the rest of the plant. The mains can get very heavy. Think a beer can on each main top with a flimsy stem structure. This is one plant that is better to spread out in a net vs trying to control letting them go vertical. When the tops get heavy and are not supported they can split the lower main stems so keep them supported late in flower.
You are doing great with the grow thus far and as always my posts are based on my experinces. You and others may have a different experience.
Back left is a Trainwreck plant that I bound together to keep it out of the other plants in the tent. You can see what happens when you force it vertical rather than spreading it out. I am not sure of the weeks in flower with this one but looking at the tent I am estimating these at about 5-6 weeks in. I typically run them 9-10 weeks. They tell me when they are done.
better than you are. You still have to water/ feed correctly. Know enuff to tell if there’s any issues with your lighting, temperature, humidity etc. So don’t sell yourself short bromigo cause yer doing a great job 
. Happy growing. CL
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