So, basically, I think your tap water should be fine as-is. A few more details I could go into regarding it, so let me know if you have any more specific questions.
As far as nutrients and feeding...my plan as a first-time grower is to aim for "don't kill my plants and get at least a modest yield" vs. "optimize everything and get biggest possible yield on first try." I think we're more likely to burn up our plants with too much rather than kill them from too little. I'm starting with Fox Farm's Ocean Forest and may add a top dressing. That may be enough on their own. I'll buy Fox Farm's recommended feed mixes, in case I need them. I'm still deciding on exact approach, but may just error on the side of safest / simplest first time around.
Based on where I'm at now, though - my general advice for you would be:
1) To paraphrase ManoGreen's guide - probably best to just stick with the recommended feed schedule from your soil vendor (Biobizz feed schedule is
here). Even if you don't use their exact schedule, looking at what each is adding and when will at least give you an idea of how their base soil performs over time.
For example, I looked at Fox Farms feed schedule and multiplied the weekly amounts by the individual NPK ratings of each product, to get a sense of how much total additional NPK they were recommending and when. If I go with top dressings instead, or other brands, I'll use that as a general guide.
2) Always best to ease into any feed schedule (e.g., start with 1/2 the recommended strength for first one or two feedings). Ultimately, the basic approach always seems to be "observe plant response and adjust accordingly".
That goes against our "I want biggest yield ever" instinct, but if everything works out for the first grow and I do a second grow the same, then I may start with full strength, etc.
3) Read through symptoms of deficiencies, lock-outs, and burns. You won't remember them by heart, but it'll at least give you some idea of what to look for in case there are any issues with your final approach. If something does happen, the simpler approaches (e.g., soil only, no amendments / dressing, no feeds) should probably be more likely to cause deficiencies, the more aggressive approaches more likely to cause burn, the "mixing vendors and products" approaches to cause lock-out and/or burn.
It could be useful to use one plant as a control, or at least lag 4-7 days behind the others, to evaluate the impact of any additional feedings / nutrients. If you have one without any additional nutes that's not dying, then you know any issues with others are more likely lock-outs / burns instead of deficiencies, etc.
4) Keep the journalz.
If you make it through a grow with a certain feed schedule, then you know it at least works. You can then try tweaking it on the second grow and have a baseline for what works, and a reference point for diagnosing any issues with the revised feed schedule.
Similarly, you can just follow another grower's feed schedule as a baseline for what works...if you can make sense of it.
Here's a thread on Biobizz light, but it seems to be "my past two grows didn't work, so here's what I'm gonna try next" without any final confirmation of whether it worked or not...
One good ale = a baked potato in carbs and my blood sugar would go ballistic.
