Re: Things to buy + other advice
#11
Sounds ideal for goldfish.
Personally I wouldn't bother with an air pump. If you have enoguh surface agitation from the filter that will give you enough gas exchange. I'd also second the eheims as excellent filters. You'll replace the sponges when they fall apart (which should take years) and the fine floss every couple of weeks (as noted buy it in bulk).
Amazon Swords like it a bit warmer than goldfish do, so it may not last that long for you. Java Ferns would be a better choice, and
Elodea,
Ceratophyllum, and
Lagariosiphon as fast-growing sacrificial plants.
A 25kg bag of gravel should be fine. Just remember to wash it twice as much as you think it needs.
The size of the pellets shouldn't matter too much 3mm will be fine for the size of goldfish you're looking at.
I'd go with a 5ml syringe, rather than a 10ml. You won't need that much ammonia to cycle the tank.
Other than that you're good to go. Brushes for cleaning pipes, etc, can be picked up as and when you need them.
Loaches, Barbs, Minnows & Shrimp! Oh My!