That is a 20lb bottle. I don't know how long it will last but I'll let you know how long it does last. Plant on the right has at least 2 set of leaves but isn't going up, and the plant on the left has grown at least 3/4 in the last day. Center plant hasn't done well so I put and bean in that pot yesterday.I think the plant on the left got a little brown tips on the first set of leaves. I didn't have a pH meter and I think that is what caused the brown tips on one set of leaves.

The pH was almost 8 so after a reservoir change I got it right about 5.6 to 5.8. pH down by Advanced Nutrients is what I used. I mixed my other nutes at 1/4 strength until week 3 or depends on how plants look.