Yes, they are simultaneous. Do I need to increase lighting when I get my fertilizers or just keep it at 8 hours no matter what?

I'm trying to figure out exactly what I need to be adding to get my water up to par. I saw the measurements of fertilizers for non-co2 tanks somewhere on the board, I'll find that again. Also what I'm trying to figure out is how much calcium and magnesium I need to be adding to bring up my gh and kh to decent levels. I'm adding a little at a time until I get it increased to appropriate levels, but since my tap water is 0 on both counts I need to get a solid measurement of what I need to add every water change for calcium and magnesium, same as the fertilizers. Pretty much my water is just like distilled, the pH is 6.4 out of the tap, no buffer at all. It apparently has tannic acid in it, that's what I was told, due to the yellowish color. It's obviously not iron. The water is so acidic that my in-laws house which was only 15 years old, had to be totally replumbed with plastic pipe, the copper sprung leaks all over the place. So there's probably copper in my water too from the pipes here.