@CassCats have you kept these?
I've kept Taiwan lilies in past, currently have an Aponogeton... I use liquid fertilizer only.
So the deal with plants... root feeding is a bit of a myth. Aquatic plants are opportunists and will take nutrients through their leaves and through their roots, not one or the other, but
both. The nutrients in root tabs usually just disperse into the water column anyways. Aquatic plant roots are mostly to anchor the plant in place so it resists being washed away from the substrate. That is their primary purpose.
BUT, a lot of the plants people recommend root tabs for are heavy nutrient users. So people find it easier to dose a root tab simply because it's a slow release type of nutrient supply.
You could accomplish growing bulb plants and other plants like swords by only using liquid fertilizer if you are diligent enough.
But, if you are forgetful or dose infrequently, OR your plant demand is too much to keep up with, then having additional nutrients available is helpful and this is where root tabs are useful.
Myself, I just adjust my dosing routine based on the plant needs, so even if the bottle says to dose once a week, I'll dose more often if the plants show they need it, while also monitoring my water parameters. This could be too hands on if someone has a tank filled to the brim with fast growing needy plants and find themselves needing to dose almost daily, so understandably someone may not want to go this method.
To sum it up: root tabs aren't necessary to the growth of the plants, but can be beneficial. Monitor your water parameters, if you have a nitrate spike then you've got too much nutrients and need to cut back. This goes for adding the tabs, if you notice higher nitrates, then reduce what you add.
Either brand of those capsules are reputable, good options. I've used Thrive liquid fertilizer in the past, it's fantastic stuff, I'd have no reason to believe any different about the root tabs. I use a Canadian made fertilizer now, it has the same results as Thrive, but it's not available outside of Canada.
