All great points, every grow is different, as well as every strain is different. I recently realized that some of my seedlings took off and immediately began growing, while others were slow and took much more tlc and problem solving. If you've gotten a decent light setup as well as soil, etc. I bet she will pick up for you. Those first few weeks can be frustrating getting everything sorted out, however if your ph is good, your heat reasonable( 80 could be a tad high), and you're not over or under watering, I feel confidant the grow will pick up. I definitely agree with stick as checking the light specifics, many leds claim to be much more than they are. Good luck with your grow, I'm fascinated by the space bucket approach.
A non-oscillating fan blowing on a plant can cause wind burn. I suggest getting an oscillating fan. The plant needs fresh air circulation. A constant fan on the plant wont allow the plant to use up the co2 (non sealed room) around its leaves.
Ive noticed that during winter I only need to water the plants once a week or so.
Is that OK for a SpaceBucket with a ufo led?
What's better? several small waterings or a big one once a week?
Im using 1,25L a week, should I try to break that quantity to 2 waterings?
99% or so of the water the plants drink is later transpired. Because of your low temperatures, the plant is transpiring very little and so, its needs of water are greatly reduced. It is not a matter of UFO vs HID vs whatever; if you can raise your temperatures, then your plants will start drinking more water, the ideal situation is to water for 4 to 5 days. For your temperatures 1.25 liters a week is too much; I would give it half a liter and expect it to last 3 or 4 days. Having the soil wet too long can (and usually will) attract bugs.
If you can raise your temperatures, you will see an increase in growth (or bud development) speed; try to lower your exhaust fan speed or have it on a timer (15 in on / 15 min off).