Seedling- respectful comments

liquid silica is highly alikine, the best one and happens to be the most expensive in liquid forms is Monosilicic Acid, their are some forms of amendments of Si, rice hulls, DE, Wollastonite. They take time to break down and DE has the added benefit of being a anti bug deterrent when its dry. I think its good to have in all life stages its a supplemental building block but not necessary. Helps em bulk up and build defenses from pests.

It's a popular supplement but I've never bothered using it. I'm a fan of the "less is more" line of thought. I don't add extra products just to add them. I need a reason to. It's supposedly helps strengthen branches but weak branches has never been an issue I've had problems with in my personal grows. We use it at work and it doesn't seem to help THAT much IMO. Of course at work we're also doing THICK canopies that are massively crowded together, it might be worse without it. Most of those plants still can't support their own weight though. In excess, silica can make your limbs too ridged and difficult to train too.

Most nutrient manufacturers recommend silica only for the flowering phase...........

just like anything else.. there's a goldielocks zone that is helpful ... too much is never good. if i recall you only need about 10-20ppm of silica in a soilless/hydro context. Some forms of delivery are more likely to cause a toxicity than others.

You can give silica to seedlings with no problems. The only thing I’d mention is that it can make the branches a little harder to manage if you do lst when they get bigger because it does make them harder/thicker/stronger. Still totally doable, just a bit trickier

On my current run I’ve used diatomaceous earth in my soil mixes right from the beginning. I don’t see why you couldn’t use silica right from the beginning.