Bristlenose Plecos and green beans.

I'd go for more than just green beans--zucchini, carrots, etc--but a diet of frozen veggies plus what algae the tank produces should be fine.
 
Try zucchini once in a while. I haven't had a pleco that hasn't loved zucchini, other veggies seem to be hit or miss depending on the individual pleco.
 
My pleco loves thinly sliced cucumbers. I put a few slices in the tank on weighed down with a chip clip a few times a week and the next morning everything but the skin is left. It's funny because there's just perfect rings of the skin left.

You said you have baby bristle nose plecos? If you would consider selling one, pm me and we will see what we could work out!
 
I would probably supplement some with wafers, but veggies are great for BN plecos. Once they get a little size on them, BN plecos are very easy to ship.
 
Yes, vary the diet, not just green beans. Zucs, blanched Romain lettus, and green beans have been my BN food of choise.
 
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