Re: "tap water", it depends on what you mean. Are you in the city, with chlorine in the water? If so, then you should at least be letting the chlorine evaporate. Are you in a rural area with a well, like me? If so, is your water soft or hard? If it's hard, are you using a softener? If you are using a softener like me, then you are adding bad salts for plants into the tap water. Sometimes I add 15ml of well water into a gallon jug of distilled water to kick in some random nutrients, but if I base my entire watering schedule off it, my plants will die. I'm about to build a still to distill my own water, as I've been paying $1.88 per gallon jug, needing 5 jugs a week. The final piece, a teapot, is literally coming on the slowboat from China... as soon as it gets here I'm going to finish the still and post a pic in one of my diaries. Total cost is about $40... and yeah it adds something else manual to the process, but doesn't take much to boil water in a 1/2 gallon teapot...
Re: lighting, I just use full spectrum at all times. The plant will use whatever light it needs and ignore the rest from my experience. 30 years ago I even grew and flowered a plant using nothing but a 2-foot long fluorescent tube. There may be some who argue you can get advantages by using certain light at certain times, but it's definitely not necessary, it's something you can experiment with later on after you grow some plants successfully. Just blast full spectrum on them! If you think about it, the sun is the same colour in the sky in autumn as it is in summer... maybe there's some slight shifts due to the changing angle of sunlight cutting through the atmosphere, but it's still the same star emitting the same stuff.
Remember the K.I.S.S. principle in life, which stands for "Keep It Simple, Stupid!" ... the more complicated you try to get, the more variables you have, the more problems you open yourself up to especially without the experience to back it up and fix if things go wrong. In all things, not just farming! :)
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