Safe bro I would go with 2 x 15l or 2 x 10l in that space under a MS0006 if u wanna grow more plants try 4 x 6l Airpots.
Thanks for pitching in man, how can I not take on board your advice after browsing your awesome results for months?
4 does seems like a nice idea and I think I planned on it initially, I just thought the overall yield would be better from two bigger plants, I may be wrong! Maybe I can save the two 15L for when I have some experience under my belt..
Does anyone have any suggestions in regards to watering based on that limited info above from the local council? Ph down could be my biggest investment if I need it for every watering! Take it easy