It depends on the size of the plants... If it is going to be a big ass plant go with a big ass pot. I find it is best to water at least once a day in coco, flooding to 10-20% runoff, so if your plant can feed once a day in a bigger pot without getting too oxygen deprived down low then that is a plant with the size to utilize the bigger pot (if feeding daily). Coco is awesome for its ability to retain oxygen in the root area even with a well saturated media, so I like keeping her nice and moist with fresh food daily, instead of wet-dry-wet-dry. But then again that "dry-out" cycle can have a nice effect too. Comes down to experience and then preference. But a bigger pot will mean more nutrient cost, don't know your budget but just something to keep in mind. Just for example, a run that I just saw had sour diesel in 5 gal fabric pots. these were big ass plants and the grower was watering every other day to 10% runoff. each feeding of 6 plants required 15 gallons of water to achieve appropriate run off ratios. The grow went very well, however I feel that a daily watering would have sped things up, increased yield and would have been less stressful for the root zone (not that his plants appeared stressed at all, they were beautiful!). I'm not saying one works and one doesn't, more like very good vs a bit better. but my humble opinion the 11L pot will be more than adequate for a plant 3-4 ft tall, feeding once or twice a day. I'd say 18L pot would be better for plants that will finish 5-6-7 ft tall feeding once or twice a day. Hope that helps a bit, sorry too run on... Damn Dabs!