Mango Lassi & Serious Kush

I germinated one Mango Lassi and one Serious Kush with the paper towel method. Afterwards I planted the seeds in a 1l pot of a light soil mix. After two weeks I transplanted them into 11l pots and started to add the Bio Tabs products into the soil. At this time I planted a second Mango Lassi seed directly into a 1l pot of light soil. After another five days I topped the two older plants. The Mango Lassi has some purple stems, but I don't know if it's a deficiency or due to the genetics. The Mango Lassi is tall and not really bushy. The Serious Kush has big stems, is way smaller and is really bushy. I did a small defoliation on the SK.