Using this method, I find it amazing that plants are able to adapt and support their oxygen needs from within the jar itself. As the water and nutrient level drops, plants obtain the necessary oxygen from the empty space in the container. When the water levels get real low, I generally fill the jar only about halfway up to maintain that space for oxygen uptake.
I currently am trying out several grow light options. On the low end I have put $17.00 grow bulbs into the hanging fixtures in my kitchen. They work quite well. On the high end, I like this hanging dedicated Cree lamp. It gets the job done during the long Alaska winters and doesn't give off that purple growlight glow that I don't care for.
Just like a fish bowl, you will develop algae if sunlight gets in. With too much algae, your roots will suffer.
Maxi-grow is my go-to nutrient solution. I am not looking for sophistication so I simply mix a teaspoon of dry nutrients with a gallon of water and off I go. I have used Anchorage city water (Eklutna Glacier), well water (very hard) and water from my fancy reverse osmosis system. The results are the same, in my experience. I'm sure this is sacrilege for some growers.
Nope. Too lazy.
The only time I have had pest problems is when I have brought in a plant from outside. Sometimes even a cutting taken from an outdoor plant will bring in some bugs. But in general I have no problems with pests.