My shrimp tank is approximately the same size and I would recommend a nano sponge filter rather than an airstone.
It isn’t strictly necessary but having the additional filtration and water movement goes a long way.
If you want to go without, you will have to do frequent small water changes. Large water changes are out of the question as shrimp are sensitive to fluctuations in water parameters.
Also, as someone from a very hard water area, I would recommend investing in a RO water unit. I was losing shrimp regularly until I switched. Turns out that each water change was adding more concentration of minerals in my tank and that was not good for my shrimp.
For more info about this, you can check out the marks shrimp tank and shrimp mania YouTube channels.
I say it doesn’t need a air stone, and if you let the plants grow for 2 or mor months you probably don’t even need weekly water change, I have a 5 gallon chocolate colony with no air stone I do water change like one every few months they still doing great, I even rescaped it recently like 2 months ago never touch it since.
Lottie_Belle 
My shrimp tank is approximately the same size and I would recommend a nano sponge filter rather than an airstone.
It isn’t strictly necessary but having the additional filtration and water movement goes a long way.
If you want to go without, you will have to do frequent small water changes. Large water changes are out of the question as shrimp are sensitive to fluctuations in water parameters.
Also, as someone from a very hard water area, I would recommend investing in a RO water unit. I was losing shrimp regularly until I switched. Turns out that each water change was adding more concentration of minerals in my tank and that was not good for my shrimp.
For more info about this, you can check out the marks shrimp tank and shrimp mania YouTube channels.
I say it doesn’t need a air stone, and if you let the plants grow for 2 or mor months you probably don’t even need weekly water change, I have a 5 gallon chocolate colony with no air stone I do water change like one every few months they still doing great, I even rescaped it recently like 2 months ago never touch it since.
This is the nano sponge I use: https://a.co/d/hubAIVE It’s good up to 3g and much much smaller than the pics show.