Do I have to use special Nutes

I am a new grower, using soil, a 400watt mh and hps set up, using the mh for veg currently. (HPS will later be used to flower) Do I have to be using nutes?

I am currently using aquarium water from a stable aquarium that grows its own freshwater plants. I make sure to scoop up lots of fish poo and stir it often. I use a grocery store found fertilizer, i think its miracle grow- i am too high to get up and look so lets run with that, its heavier in nitrogen and i intend to use that for veg. Since I am only at about 4 weeks growth (slowed by my humble beginnings read the start of the journal for more) around 10 inches height I am mixing a very light mixture- and have only done so once at about 2 weeks in.

For flowering, I am planning on switching to a potassium based fertilizer meant for african violets that is high it potassium and potash (which I have heard will slow the verticle growth in that late flowering stage)

Is this a bad idea?
Do I have to go buy the goddamn nutes?
and which ones?

And how about carbonated water? wtf? heard a lot on this site? As of right now I am planning on spraying the leaves with it- through vegetation- stopping of course for flowering.

Sorry for such a broad post- but I need it in the context of my setup so I wanted to reveal all my details and get a detailed explanation?

the miracle grow is 15-30-15, but only a little was used, and now that I have seen that it is actually more potasium i wont be using it again in the veg stage, should i use it for the flowering stage, alone or with the african violet stuff?

another one i have, but havent used it an expert gardner brand 24-8-16. should i use this now since it is high in nitrogen? havent yet, but barring anyones convincing no i will be using it when they hit 18 inch mark
Questions need answering