another vote for staying away from plastic spray paint. it doesn't stick to bins. as soon as they flex, the paint comes right off. Real78 is right, use tape and save yourself some money and hassle or you'll have flecks of paint everywhere, including in your nutes.
i've got a ebb and flow set up and i was originally using 18 gallon rubbermaid tubs but i'm tinkering with 5 to 7 gallon buckets now which hold enough liquid for at least a week (for my set up). i got the 18 gal. bins because i wanted to be able to leave for three weeks. i've tested it and it will work, but it's a pain in the *** to haul around that much water. that's why i'm switching to either 5, 6, or 7 gallon buckets - with lids! when i go away, i'll just bring out the larger bins.
mG2