Getting an air pump is extremely important as you need to oxygenate the nutrient reservoirs. However, getting only an air pump won’t suffice as you need a lot of other components along with it too. Primarily, you need to get airline tubing, as well as air stones in order to make any use of your air pumps.
The airline tubes that you need to buy should be made out of garden-safe plastic which is safe to use - many growers prefer buying aquarium tubing for these purposes which is black in color. Getting a dark/black color tubing has a lesser chance of catching algae. Besides this, the air stones are also very important and they need to be ones which create as small bubbles as possible! Smaller bubbles have a smaller surface area and can hence travel faster. These are a few things that you need to keep in mind while buying air pump accessories.