Can you share a picture of what your pond looks like? The majority of a goose's diet consists of grazing (grass), but they do need supplemental feed. Some people feed them once a day, some people let the geese have access to feed at all times (and the geese eat it whenever they feel like it). I dont do the free-access to feed because I only have 2 geese & dont want to inadvertently feed other critters. Instead, I give them their feed in the evenings when I put them in their shelter - most people dont leave food in their shelters overnight, I only put as much as they'll eat - they used to leave food and I gradually lessened the amount to where there weren't any leftovers. Geese will need access fresh water during feeding time.
Here's a good link that talks about types of feed (its geared towards Sebastopol geese, but can apply to Chinese) https://www.backyardchickens.com/t/611666/feeding-for-feather-quality One of the differences between waterfowl feed vs feed for other poultry is the protein level, waterfowl dont need as much protein as say, chickens, more so when they are goslings, as too much protein may lead to angel wing - I'm assuming the geese that you'll be getting are adults? For adults, in my opinion, the protein issue isnt a big deal since their 90% of their diet will be grass. Mazuri waterfowl feed by Purina is supposed to be really good, but its crazy expensive where I live, followed by Flock Raiser. My feed store carries "Trip-L--Duty" by Manna Farms which is cheaper and comes in smaller quantities; I add rolled oats to the mix. Oh!! And a note about corn that I learned here on the goose forum: it doesnt pack much nutritional value, so if the geese you acquire are at healthy weight (don't look starved) feed in limited amounts. You might also find this thread helpful, https://www.backyardchickens.com/t/586695/what-does-your-goose-coop-look-like
