Hey green,
The lucas formula uses floraMicro and floraBloom at a ratio of 2:1 throughtout your plants life. You start it about 2-4 weeks into veg at half strength, but that all depends on the genetics your growing, all plants are different. Basiclly floraMicro contains enough nitrogen for veg growth, and when added with bloom the plant gets all it needs at a very basic level. This formula is made for beginners and is very hard to fuck up, but remember LESS is MORE when it comes to growing your girls. I'm learning that the hard way lol.
The formula was created using RO water so if you do as well results should be fairly constant, assuming you have control over the growing environment. Tap water should be fine though unless you know of any specific reason to not trust it. Just make sure your PH is right before letting your girls touch the water. Also, once you have "dialed in" to what your girls like, you can add other nutes and experiement a little. Again LF is a very basic nute plan and is great to learn from. I plan on using it for my next set up, I'm hoping to make it a perpetual grow but we will see how that turns out
I'm tired and kinda high so I lost my train of thought, but if I missed anything sorry. Gl with your future grows!
