Strange distorted growth on top shoots

I need some help identifying what the problem is with my 4 plants, the new shoots are distorted and I can see the new shoots are small and the new growth doesn't look right . All in 5 litre fabric pots in pure Canna coco. I was feeding 800 EC of Canna coco, 20 ml Rhyzotonic, 2.5ml per 10 L of a calmag product and I started to use a Cyco Silica at a rate of 1m per litre and PH of 5.8. They are in a small 85 x 50 x 80 clone tent. I have a 4 inch inlet fan and a 6inch outlet fan one small 7inch osculating fan. I'm using a 2 foot T5 starlight 220 watt light which is almost 12 inches from the plants, there is no stretching with this distance. Because this problem is getting worse I have stopped the calmag and silica and I'm now only feeding 1000 EC Canna coco. I will be transferring them to the larger tent but I really want to find out what the problem is. I have searched and it doesn't look like a nutrient deficiency and doesn't look like a Calcium or Magnesium deficiency. Any help would be good.