Filtration specialsInternal filters are a must for large aquariums expecially those using canister filters. The canister filters(external type) have a tendancy to clog up quickly if they are not cleaned regularly. However I have found that none of them are user friendly when you have to take them apart. I have 30 years in the industry and still have a hard time putting them back together. Also every time you take them apart they have a tendancy to break somewhere- either a lock down clip, o ring, or in valve. So to remedy this I recommend an internal filter. The Jebo ap 120fc and 180fc are great for this. They fit in the aquarium in a corner and use hight speed powerhead motors to prefilter and pull most of the waste out of the tank. The jebo models come with 125gh and 200 gh powerhead and then filter attachments and media to prefilter.In a saltwater tank they work great when using protein skimmers and wet dry filters to pull particles out that will clog the units. They also have a dual purpose by creating wave action when attached near the surface. Both these units are problem free and I give them four stars. The penn plax cascade 300 filter is one of the most economical and effecient units for small aquariums and turle amphibian tanks. It needs one inch of water to operate does over 70 gh. It includes a air injector attachment so it can aireate and filter. It is great for small aquariums for both filter and air. I give it four stars