Low electricity arctic sativa grow

Selected two of the best looking seedling to grow further, these are Critical Kush and Jack Herer. Plants are still very tiny, I've been having problems with very low humidity (30%) and cold (max 19C in the tent). Conditions are very arctic, so this ain't easy...I'm growing in a basement that has pretty much fridge temps. Trying to get humidity and temperature higher with a clay pebble tray and a heat mat under the pots. Nutes: half strength biobizz week 1 nutrients. EC a bit high, still learning to get PH right... Also been thinking about the crappy light I have. It has only around 60 actual watts and ofc the purple color is not optimal. What do you think? This the one I have: https://www.lumeri.eu/collections/panels/products/lumeri-lq300