12 days old - slightly yellow leaves - help

Ok so my plants are 12 days old and they have been doing pretty well, I have noticed in the last 2 days that there are yellow patches on both plants I think this is nitrogen deficiency?

I have Canna Coco Part A+B I haven't used it before and the instructions are not clear.

I would like to know: how much of each part I am supposed to put in (ml) in how many litres of water
How much to feed each plant (ml)
How often to feed nutrients
Does water mixed with nutrients have to be PH'd

go 1/4 strength at first, and work your way up slowly in increments to full strength.

Yes, yes, and yes. Ph your water as well as your nutrient solution. Feed once per week.

All nutes should tell you on the back of them how much to add to a 1 gallon jug. Get some pipets to get the ml's perfect. You should be fine though dont wurry about the yellow leaves it happens. Just pull them when they die. PH is a huge thing though, luckily my tap water is perfect. Get a PH meter and use tap water. Get some ph up and down and youll be all set. hope ive helped