Nice! My 2 pots are 2.5 liters each and I've been thinking about maxing out the amount of soil by just using a single container like you're doing.
I recently started packing the pots so that I first fill them halfway with uncompressed soil, then saturate it with water so it gets compressed and then fill up the rest and only lightly water the center when the seed has been planted, maybe 100 ml/day at first, slowly working up the amount. When the soil level is lowered I just add clay pebbles. Growth has been very nice for the first few weeks that way.