Have one in my small betta thank and one in my 5 gallon betta tank. Have been using it to a couple weeks and it seems to work so far. In the small tank it has to be on the lowest setting or my betta can't handle it so I wouldn't go smaller than a 2 1/2 gallon tank. For some reason it makes a louder noise in the larger than so I put something between the tank wall and the bottom of the filter on the outside.

So far, so good with this aquarium filter! This is the third different type of filter that I have tried for my aquarium. The other two brands that I purchased first broke within a short amount of time. I was understandably skeptical about this one being any different.

However, this Penn Plax Cascade Hang-On Aquarium really gets the job done! It's the quietest filter that I've tried so far. The sound is actually pretty relaxing. Instead of a horribly loud, electronic humming noise, this one sounds like a gentle waterfall.

My fish tank was noticeably brighter and more clear within the first 30 minutes or so after it was installed and turned on. By the next morning, the aquarium was crystal clear. It also has an adjustable flow setting that's proven to be useful. Not only does it help to create plenty of aeration, but it can be set to a lower volume during feeding times or other times when you wouldn't want as strong of a flow of water rippling throughout your tank.

So far this filter has been beyond fantastic. Bought the 200 for a 36 gallon tank since I want to make sure my tank is being filtered as thoroughly as possible. Though it's only been hooked up in my new tank two days it seems to be doing a nice job at keeping the tank clean and was pretty quick at getting rid of the yellow iron tint my water had. And the best part? It's SO QUIET. It has such a quiet hum that at first I thought it wasn't functioning properly but it is. It's just quiet and it works. I'll update if I encounter any issues but I'm very happy as of now.

I bought this filter for my small tank (29 gallon) to replace another power filter that was dying of old age. I like this one very much. It is strong, effective, and super quiet. I like the flow adjuster, as well. The media basket has plenty of space in it.

When I first set it up, I used the 2 cartridges that came with it, (you're meant to use 4) and was not too happy to see water bypassing them and flowing straight back out around the intake pipe. I stuffed some media from my old filter into that part of the basket so that there would be filtration of that much, anyway. I also didn't appreciate how short the intake tube was and how easy it is to fall out. My water wasn't looking too good, even though it tested fine.

BUT... a few days later, when I replaced the included cartridges with cut-to-fit media, the bypass stopped immediately, and the flow overall improved greatly. I stuffed that generous basket full, which didn't slow it down at all, and my water is now so clear it looks like my fish are swimming in air!

Still not thrilled with the too-short intake tube that falls off anytime I bump it with the gravel vac...at least it's easy to put back on.

I've only had it a week so no input on durability, but it's perfect so far. No leaks, quiet, and plenty of room to use your own filter media combo. The only reason I gave just 4 stars is because the filter cartridges made for it are not very good. Thin, sloppy fit and much of the water goes around it. I just buy media pads and cut to fit. Very easy, WAY better filtering, and cheaper in the long run. A 1/2" thick layer of carbon and a 1" thick layer of fiber fits perfect and flows great. I have it on a 5 gal betta tank and plumbed it over to an undergravel pickup on the opposite end of the tank and it has plenty of power to draw it through. Looks to be the same flow as with the regular pickup tube. My water level is even a couple inches low right now since it's a new tank I'm still setting up so the pump is working harder to lift the water than normal and should flow even better once I finish fill the tank. As long as it proves durable I'm very happy with it.

Update: It's been almost a year and it still works perfect. Silent, no leaks, no probs at all. Now 5 well earned stars. I purchased the Cascade 80 a couple months ago and it also has been perfect.