Need help on the use of mars hydro ts1000 (first grow first use)

Let the plant tell you.. If internodal space is too large, get light closer and or increase intensity -- both can work. Looks like you are using this for more than just a couple plants or plant to (i see more than one pot in pictures)? So, it likely needs to stay at same height for consistent coverage. Pick a height that provides a suitable footprint, then dial in power as needed. That'll be the most efficient way to go as far as watts used and what the plants need. 30cm is fairly close. As the canopy gets larger, you may need upto 50cm to cover it all. Keep pushing power as best you can and take some notes at various stages... it'll give you some familiarity the next seed you pop.