I have learned quite a bit about coco medium but I am not sure what you mean by "11L air pots" and "2.5Lper hr of air". It sounds like you are planning on running a hydro setup with a top feed into 11L coco dilled pots. Is that correct? then the air you are talking about is going into the resevoir of water?
If you are using Canna nutes, unless they are organic nutes and you are intending to run organic, I wouldn't recommend using the beneficial microbes that GreenEyes is talking about. These is nothing wrong with using those if you are in standard soil and/or you are running all organic. But if you are using hydro/soilless/chemical nutes, you will kill off the beneficial microbes before they can do any good. In that case just run the chem nutes roughly according to the schedule that they provide.
To expand further on the nutes per yer request; You should not feed the seedlings anything for a couple weeks. The reason is that they are very sensitive to chemicals at the seedling stage before the roots have fully developed. The little round leaves that first emerge are the "feeder" leaves called cotyledons. Those actually serve the purpose of feeding the seedling until it has developed roots to feed itself.....Once you see new leaves emerging and the plant is starting to take off growing, you will see the cotyledons start to "yellow-off". This means the plant has used them up and is dumping them. That is when you start feeding (usually in the 2nd or 3rd week). If you look at the feeding schedule that is supplied by Canna, either on the bottles or in some literature, it will tell you how much of each nutrient to use and different stages or each week. I cut that number that the nutes have down to about 1/4 or 1/3 of the recommended dosage, then increase it some each week until I think the plants are getting what they need or until I see the leaf tips start to burn a bit. The reason for this is that MJ is very nute sensetive and each strain has a different appetite. It is always better to under feed them starting out than to over feed them as it causes fewer problems. It will take you a couple grows to really learn the plant and what it needs, so don't be suprised if you have problems with this grow (everyone has learning pains starting out) But we are glad to help you get through the learning curve.
Tell us a bit more about your set up per my questions so that we can give you some more tips
