All planted tanks, unless keeping the least demanding of species, will need some type of fertilizers.
Need for macro nutrients is driven by light and supplied by fish waste and uneaten fish food.
low light = low requirement for macros
lots of fish = high supply of macros (with the exception of K will frequently be deficient if relying only on fish waste)
So you can get away without macro nutrients assuming you have ow medium light and a decent fish load. Though I would still dose potassium.
But even with the best substrate in the world you will eventually becime micro deficient.
ALL tanks (with very few geographical exceptions) will become deficient in micro-nutrients over time. The first deficiency most see and report in my experience is iron.
whether you add the fertilizer as a liquid or a powder is immaterial. But I would suggest a buying dry unless you like paying for and paying to ship water.
Look up nilocg sale thread for dry ferts. You will be shocked how cheap they are compared to the liquid crap