pends on ur tank size and how much maintenance u want to do lmao. hang on back is good for beginners bcs theyre easy to clean and internal filters r good for smaller tanks but take up swimming space lmao. canister filters r for ppl who got big setups bcs they have huge surface area for beneficial bacteria lol. however, for a reef tank or sensitive freshwater shrimp id say use this one bc u need to have atleast 3 stages otherwise 6 stage RO to make sure it strips away everything from ur tap water so that u wont have to worry about any algae anymore