The 500-800 should be fine, just feed a bit more is all. In an airtight container with minimum extra headspace, in the freezer. This helps retain vitamins, slows oxidation, and keeps fats from turning rancid etc.
Forgot an important thing - Take a bit of tank water and presoak the GPs in it for a short while before feeding.. just a couple of minutes. Some claim the air releasing from it in the belly can kill. Haven't seen it, but better safe than sorry.
Also I would get NLS or something similar as well to mix in the feeding if you wish.. although GP is awesome and high in protein, it is a little low in fiber, other food mixed in the schedule will help on that. But overall, GP is still ideal.
Golden Pearls:
Crude protein: 60% min, lipids: 8% min, ash: 15%, moisture: 8%, vitamin C: 200ppm, Vitamin E: 400ppm, astaxanthin: 500ppm and the ingredients - brine shrimp, squid, shrimp and fish proteins, animal protein, purified fish oils, phospholipids, astxanthin, vitamins and protected minerals, antioxidants, and immunostimulants. You aren't going to get anything as good as that from common pellet/flake food.
They come in different sizes, so you will have to look to see what is best for you. Typically the 800-1000 microns would work.. the smaller microns are for fry. If your guy is small you can go for the 300-500 micron size, it's similar to NLS Grow in size.
According to the product box, they are a sinking food, however they are entrained with air so they don't actually sink... More like float in the water column forever. Since they have this air trapped in them, when they float across the water column they appear to move similar to that of a live food, which tends to make carnivorous fish (like bettas) go nuts.
IMO, these are way better than NLS - NLS may be cheaper and may be easier to find, but over all quality, GP is better. Can order from Kensfish (.com)
or from the San Francisco Bay store.