Unless you have a huge res and plan to swap it out every few days, the liter size grow and bloom should get you to harvest. Even in hydro. Just remember to keep the ppm low. About a 1/4 of what the manufacturer recommends. I don’t grow in DWC (if that’s where your going with the auto pots) so maybe someone that does will chime in. I grow in DTW coco. Vegged 6.5 weeks from seed and flowered 63 days. Swapped out the 45L res once a week. I ran out of grow (liter size) on my last change before flower. But I think that’s because the first few I mixed up were a bit hot. If you are confident in your skills, the liter size will be fine. If not and you think you may need to remix a res or two through the grow, I would order at least an additional 500ml bottle of grow and bloom. That will comfortably get you to harvest, and still not waste too much if you decide to switch nutes on the next run. Especially in your situation as it sounds like you can’t just run down to the grow shop for more. Good luck.
