Clay pebbles for Hydro??Dunno bout that,I dont do Hydro bro..sorry. Yeah I wish we were Metric too to be honest..it'd be sooo much easier..lol.thats why I have a measurement chart around..lol.Liquid mostly. but for 5 gallon Buckets like worker paint Hydro 5 gallon buckets?Or standard ole trade gallon Buckets?smaller trade gallon buckets are 0.71 true gallons for every single gallon.so a 3 trade gallon pot for example is 2.2 Gallons true.
But I got a 1.5 Cubic Foot bag and got 3 5 trade gallon pots filled.And one and a half 5 gallon hydro/painter styled buckets.you could get two per bag if you ammended it with perlite,extra used soil and so on. and leave a touch of room like HH mentioned.dunno how many times Ive spilled water over the side of a too full pot n went DOH!!!! dernit lol