I bought the 300 gallon model for my 120 gallon tank. Overkill? Maybe, but it does the job like no other air pump I've owned. I have it powering two 4-inch round air stones via 8 feet of black airline (anti-siphon valves are a must!) The pump is located in the cabinet beneath my tank approximately 2 feet below the bottom of the aquarium. It is so powerful, it is pushing air up to the top of the tank and then back down 30+ inches to the bottom where I have the two air stones buried in the rocks. (To keep them down, I used silicone to attach pieces of slate to the bottom of each air stone - it helps, a lot!)While this air pump is huge (5" x 8"), it is also hugely quiet. My old air pump was the size of a deck of cards and this one makes no more sound than that one did. The high rate of airflow makes two huge columns of bubbles. This thing is even better than I'd hoped.PRO'S:POWERFULQUIETGREAT PRICECON'SHAVEN'T FOUND ANY, YET!If you're looking for something to get air to your fish - GET THIS PUMP (300 VERSION)! IT WORKS! My 7-year-old blood parrot cichlid was a very pale orange until I installed this bad boy. He's huge and is about 7 inches long and 5-6 inches tall. My smaller blood parrots were always much darker in color, and I could never figure out why. In less than 24 hours his color changed to an orange that is almost red. I never knew he was not getting enough oxygen. Now, he looks better than ever.