I have a 20 gallon tank that currently houses 3 mystery snails and will soon also have 2 fancy goldfish. I'm going to buy a new filter that's bigger because I know the goldfish are big waste producers. I'm looking at the AquaClear HOB filter. They have one that's for up to 50 gallons that filters 200 Gal/Hr, and they have one that's for up to 70 gallons that filters 300 Gal/Hr. For 2 fancy goldfish and 3 mystery snails, would you say the 200/50 or the 300/70 would be better? I'm sure it's obvious but I need some second opinions, please.