I use 1 Tetra Whisper "40 gallon" pump for each plant (4). I recall they are rated 2 L/m (120 L/hour). I have them set on the coco/perlite surface under the plant branches, on their backs, legs (and air input) up.
They seem to do the job, and there is no noticeable noise (but keep in mind there are constant fans going, including the lights). They are pretty cheap (on Ebay), and as I did, you can start with 1 handling 2 plants, which could even work well enough.
They seem to do the job, and there is no noticeable noise (but keep in mind there are constant fans going, including the lights). They are pretty cheap (on Ebay), and as I did, you can start with 1 handling 2 plants, which could even work well enough.