Small white spots on leaves in germination phase.

Correct, roots need complete darkness to grow, clear plastic is an absolute no-no! Plus, the shape of the bottle is going to be a nightmare when it comes time to transplanting, the hour glass shape will effectively prevent the soil plug with the roots from sliding out and I suggest that when you come to transplanting time, to carefully cut the bottle off and pray that the soil doesn't crumble into a million pieces. The "white spots" are nothing, just fairly typical patternation of cannabis leaves and are of no concern. At this stage I would be giving just plain tap water without any additions or attempts to change pH, young seedlings are very fragile and I personally believe that the less you mess with them at this early age, the better. Since you are using soil, a pH range of anywhere between6.2 and 7.2 will be absolutely fine, cannabis is not some sort of delicate fern that needs everything exact, it is a tough, hardy and adaptable plant that will cope with a lot of adversity and still be able to thrive. However, you should be trying to keep the leaves dry when watering, cannabis is not a rain forest plant and does not need artificially high humidity to survive. Also, any water droplets can/may act like magnifying glasses and cause burnt patches on the leaves, especially under intense artificial lights. Black plastic pots about 4 inches across and 5 inches deep are ideal for growing seedlings and provide enough room for about 3 weeks of growth and if you are using good soil, enough nutrition that they will not need any extra feeding for those 3 weeks. And the best thing about decent black plastic pots, is that with washing between grows and a bit of care, they will last many years, reducing waste to garbage dumps and when they do finally give up, are totally recyclable, making them a good choice for environmental reasons too! Hope this helps, Organoman.