I've got a 10 gal with 1.3, and a lab tub thats a little smaller than 10 gal with 1.3 as well and they seem to breed and raise them ok.

Others have had litters eaten when no hide box was available, you might want to try giving them a cardboard box or a plastic bowl upside down with a door cut in it. I think they don't feel secure without a hide of some kind to birth and raise the pups.

Most of mine move the litter out of the hide after they are a week or so old.