An air pump is an essential piece of equipment for your RCS to be happy. I have heard of some people throwing RCS in lily ponds and surviving, but if you are going to be raising them in an aquarium an air pump is a must have.
Now you may ask which air pump to purchase. Well luckily I have done most of the leg work for you. I have tested out numerous air pumps, talked to extreme hobbyists, and weighed the cost to purchase the pump to come up with what I feel is the best bang for your buck (and quiet as a mouse!). My choice is Tetra. It not only looks cool, it’s quiet, inexpensive, and pumps out the amount of air it says it will.
Currently I have one of their 60 gal pumps servicing a 20 gal tank. It’s running a sponge filter and an air stone. With how much air the 60 gal is putting out I could at easily run 2 other setups just like this and probably a fourth!
Tetras are built to last and made to be ultra quiet. The first time I turned mine on I thought it wasn’t working correctly because it was so quiet compared to others I have tried. It’s even quieter once tubing is hooked up to it. The other reason these are great is the cost. I would not recommend purchasing a Tetra in a brick and mortar store because the price tends to be almost double what you can find it for on sites such as Amazon.