GPH for Aquarium?

Hey guys, so I have a 10 gallon aquarium right now. It has two goldfish and two bronze corydoras in it (for keep algae off the substrate). I was thinking about upgrading the filter since it is for a 10 gallon, but goldfish are messy, and one of them is 6 in long. What would you suggest for GPH? I unfortunately do not know what the current GPH is, since I have had this filter for so long I don't have the box anymore (and no, my instruction manual doesn't say it either).

EDIT: Spelling

If those are single tailed goldfish then they need a pond. They will grow well over a foot long. I have 3 that I moved to a pond. Single tail goldfish need 100 gallons per fish. If they are fancy goldfish they need 20 gallons for the first one and 10 for each other one. Either way, those fish are way too big for that tank. As far as GPH, I over filter with my goldfish. I have an Aqua Clear 70 with a 300 GPH and an Aqua Tech 30-60 with a 330 GPH. Both of these are on my 55 gallon tank containing 3 fancy goldfish. The pic above is of my fancy one that is now 9” long. Fancies normally get up to 8” long. Key: BIG TANKS! I hope this helps. Would love to see pics of your goldies.

Thank you for your input! I will send a pic or two once I clean the tank