well move the lights as close as you can those aren't very intense...
are you running the lights 18/6? maybe try giving them 24/0.
maybe throw some more light/s on them???
canna is good stuff man.... i don't think its the nutes or soil thats the issue.
I am using tap water that sits for a couple days, and I dont have a PH tester. When I first sprouted them they were in Miricle Grow soil, then I transplanted them into Bio Terra plus.