IMO It's better to feed them smaller pellets they can swallow whole. There is less waste and mess and the fish benifit from all the nutriants available. My 7" GT gets 3mm pellets and my RD & Trimacs gets 4.5mm. The smaller fish are all on 1mm pellets. If there's food comming out of the gills they're not swallowing it.
I also don't recomend feeding GT's very large meals, a couple of smaller meals is better for/easyer on the digestive system. I've been using NLS Thera+A and have had excelent results, add some skinned peas a couple of times a week and your golden.