hey/
ive got an aqua one 90L or 20g (uk) tank, 8kg of live rock 2 blue hermits, 2 red hermits, 2 turbo snails and a cleaner shrimp what else do i need 4 a perfect clean up crew? ive been told some stars more crabs+snails and a peppermint shrimp, but dont they eat corals?

my idea is to keep 2 clown fish (true) maybe another fish and a couple of corals. any idea on another nice looking petite fish that will go with clowns n corals?

any info would be much appreciated

ps is this setup known as a nano reef?

The way I like to add my cleanup crew is add as many as you need then wait and see how it goes and if you need more than add more. Are the inverts you have now doing a good job? You might want to look into getting a few more snails such as Astraea, cerith, Margarita, or Nassarius snails. If you need to add anymore I would only add maybe 2-3 more snails and go from there.

If you decide to go with two Percula clownfish in my opinion you are well stocked but if you wanted another fish I would go with a single Goby such as a Neon, Clown, Trimma, etc. I would add the fish gradually over a period of time.

Yes a 20 gallon tank is considered a nano reef as anything 30 gallons and under is a nano reef imo. What are the dimensions of the 20 gallon? What are you using for filtration and flow?