This is a cascade 20 hang on back power filter. This pumps about 20 gallons per hour and is ideal for any tank size from 4-7 gallons. 8 gallons might be a little to big for this filter. It comes with a sponge to reduce sucking in flow and also to keep bigger things (like fish) from getting stuck in it. It is quite once it gets turned on. I put it in my tank once and it was just to big for my little tank. It ran for about 10 minutes and then I realized that the outward flow was too much for my little fish in my little 2.5 gallon tank. I was unable to return it because the warehouse that I got it from can not take returns. I can do curbside drop off / pickup. I am selling it for way less than I payed for it so please do not low ball me.