Well - first off you stated 220 g - that truthfully tells us very little other than you gallonage.
When considering keeping sharks it the tanks footprint/surface are that's important - not gallonage.
While many sources may claim that you can keep certain sharks in 180 gallon tanks. Most can't - at least no long term.
For example the Brown Banded Bamboo (Chiloscyllium punctatum) is often said to require a 180 gallon tank (6'L x 2' W x2' D). But they regularly get to 36" in length, and can get up to 40" in length. I've seen video footage of a an adult Brown Banded (about 32-36" long) in a standard 300 (8'L x 2.5'W x 2'D) - the poor shark could hardly turn around, it had to use the sides of the tank, to help it turn.
Truth is if your really serious - scrap the idea of the 220 being a long term home for the shark. If maybe fine for a pupping tank, but you will eventually need a large tank/pond. Also if your serious then you should plan on have a small shark pool for one of the small benthic ("aquarium friendly") species, like Coral Catsharks, Bamboos, Eppies, or Horns. These species are your best bet - for keeping sharks. And most of theses species can be kept in small ponds ranging from 300 - 1,000 gallons, for there entire lives, in some cases even breed in the larger ponds.
Forget the Requiems - until you have lots more room, money & experience with sharks. Even small Requiems require large swimming pool size for shark lagoons. The only successful private shark keepers (that I've talked to) that have kept them. Generally have many years of experience in shark husbandary and are keeping them swimming pools(usually at least 5,000 - 6,000 gallons), for smaller species, like Bonnetheads. Larger species like blacktip reefs usually require large Swimming pools of at least 20,000-30,000 gallons minimum.
