What kind of fish?
Any filter feeders in the tank that are going to be consuming those pods?
Bigger is always better, but any size will help.
Unless you're working with equiptment you already have, I'd be tempted to just upgrade the fuge to 10 gallons, then you have a ton of room for an extra live rock chamber for pods. If the stand will fit it, it's not really unreasonable to put in a sump as large as the tank itself. Especially with a nano tank, extra volume can help matters quite a bit. Given the limited viewing area in the 10 gallon, I wouldn't want to take up visual space with a fuge up top.