Is this stocking ok?

[Gramma20]

Tank: 20 long
Filter: Aquaclear 30 for mechanical and chemical filtration, Aquaclear 50 for chaeto fuge
Powerhead: 1600 gph adjustable flow rate
Heater: Eheim Jager 125 watt

The fish I’m planning on are 1 royal gramma, 1 clown goby, 1 pink streaked wrasse, and 1 tangaroa goby. Invertebrates will be 5 trochus snails, 5 hermit crabs (dwarf red tip, dwarf blue leg, dwarf yellow tip, or dwarf zebra), and a pistol shrimp to pair with the tangaroa goby. Which species of pistol shrimp should I have? Can I have more snails and hermit crabs?

 

[James M]

IMO that’s a good stocking list.
You can definitely have more snails than or hermits or just have all snails. If I’m not mistaken any pistol shrimp should pair with the goby.
What’s the lowest GPH you can go with the power head ?

 

[Gramma20]

I’m not sure about the gph of the powerhead. Should I buy a 1100 gph one?