I've had to move all my livestock into two 30g tanks while I work on a complete rebuild of my DT. Needing good filtration I found the Fluval C4 on Amazon. Reviews were generally good, with some warning signs about noise. But noise is subjective and I liked the design. Ordered two and got them setup. Wow. LOUD. Rattling like the impeller is gonna tear itself apart. Online research said to put vaseline on the shaft - didn't help. Let them break in for over a week, no change. Great design crippled by horrible motor/impeller noise. Then somehow I stumbled upon info about the Seachem Tidal HOBs. I loved everything about the design, saw some great YouTube video reviews. I put in for returns of the C4s (Amazon is great that way) and ordered a pair of Tidal 55s. Loved them right out of the box. So many great, well thought out features and nice sturdy construction. Two major wins are the surface skimming functionality and the submersed pump location. With the pump inside the tank, under the water line, the pump is 'self priming' or more accurately, doesn't need priming. But it's all the little things that really show off how well considered the design is: sloped rim rest to sit stable on any size rim or trim tank, a label at the plug end of the power cord, heater holder, lid that doubles as a media basket drip tray, a good quality leveling adjustment screw, no specialized compartments in the filter basket - do whatever you want in there for media. 3 year warranty, plus 2 additional years with product registration. Lastly, it is QUIET. Sicce makes great pumps that run with minimal vibration. Only three things I'd like to see improved: 1) Blue plastic bits are stylish on a product photo but glaringly stand out in the tank, it should be all black. 2) The surface skimming could be more aggressive. 3) Pump cover is too difficult to remove, especially when wet. The classic AquaClear are great too, my "50" is wonderfully quiet, but having to prime it after water changes is annoying and sometimes the motor is a bit hesitant to start up. I think Seachem Tidal are the best you can do for a HOB filter right now.