OASEBioMaster External Filter for Aquariums Up to 160 Gallons, Multi-Stage Filtration, Easy Maintenance Prefilter, Quiet Canister Filter, German Engineering

The media could not be loaded. The overall design and principle of the unit is phenomenal. The execution of that design leaves a lot to be desired.Pros: Pre-filter. Insanely genius design. Easy to clean and maintain.Cons: Flow rate. Not even close to what is on the packaging. Air purging. Constantly. Somewhere on the system it sucks in air and periodically, every 5 minutes or so, you can hear the filter blowing air. If you rock the filter after a day or so, it has drawn in so much air you have to prime it to get it rolling again.Over all it does the job. Its big and loud however with the air purging. Not sure what Oase is going to do but they have some serious air leaks in the system.This was my first Oase and at this point will be my last.EDIT: In contact with Oase support. I will update once the conversation has concluded.EDIT: OASE Support was less than helpful. Flow rate is still less than desired but the air purging was solved by drilling additional inlet holes in the pre-filter tube. No more purging. None. Upgraded the rating to 4 stars now and I do recommend this filter with the easy modification to the inlet pre-filter tube.

I bought my first Oase Biomaster 350 for my overcrowded 60 gallon N. Brichardi tank to replace a SunSun that sounded like haybailer I could hear on the other side of the house. The Biomaster had many reviews touting how quiet it was, so I was a buyer. Later, I started a 29 gallon planted tank so of course I went with another Oase Biomaster 350 Thermal this time. When the other SunSun type filter crapped out on the 60 gallon I went with the Biomaster 600.I’ve never been happier with my purchases. I have NO problems with purging or bubbling. The 600 will gas off for maybe ½ an hour after a pre filter cleaning…the two 350’s never purge. All of them just sit there and quietly do their job.I believe that the purging that some others complain about are either operating error such as not getting tight connections on the hoses, not running a coat of Vaseline or silicone grease on the tank o-ring…or a warranty issue (warped lid or bad o-ring IDK?)that Oase should take care of.I also believe aquarist who listen to that foolish Irishman hacking over priced clay or any of the other snake oil biological filters on the market produced to filter the money from your pocket. I am a firm believer that the 30 or 40 ppi sponge that come with the Oase filters is the ultimate biological filter medium. The sponge allows the oxygenated water to flow throughout thus supporting huge amounts of beautiful brown biological mass. Save your money and set the filter up just the way it comes from the factory.The only “pimp” I do to my filters is drill in more holes in the pre-filter tube. I use the fine black Oase pre-filters but have added the big ugly Eheim pre-filters on the intake tubes. The Eheim filters are pretty coarse and do a great job of collecting the big nasty stuff. I clean those out about one every 7 to 10 days and only need to clean the fine Oase pre-filter about once a month. I only crack open the main filters maybe once a year (usually not necessary even that often) for a light swish around in a bucket of tank water and back to work. The biological filtration is beyond belief. Water tests show no ammonia, nitrites, or nitrates. I could really use more nitrates to help the plants but no complaints about that.I’ve had many different aquariums since 1971, running every type of filter from under gravel and the old Metaframe hang on back to now what I consider the ultimate; Oase Biomaster.

This is by far the best canister filter i have tried. Quite simple to use, sturdy materials, very silent and extremely effective.

Revised review after 1.5 years use. Contrary to what seems to be popular belief, these filters are great at removing air if you just leave it alone while it does so. Tipping the filter will result in leaks. Long runs of tubing destroys flow rate, cut the tubing as short as possible. Clean or replace prefilter every 2 or 3 days, clean the inside of the tubing every other week (you will be amazed at the difference this will make to both flow rate and fish comfort), clean the cannister every other week and rinse the media in tank water each cannister cleaning. Using a drill, double the number of holes in the prefilter tube, use 65ppi prefilter sponges and "lock" them into place using one of the plastic clips supplied for the spraybars - if you don't lock them, they will slide down during use and allow detritus to bypass the prefilter directly into the filter bed. Block the flapper at the bottom of the prefilter container by cutting a filter sponge to fit the opening and lock it in with the flapper to prevent the flapper from moving (this may make it difficult to use the primer device - I don't use it anyway) - failure to do so will result in detritus flowing out of the prefilter container directly into the filter bed and result in a buildup of yuck around the base. Anything allowed to bypass the prefilter will shorten the life and effectiveness of your bio media. Also, make sure the top of the prefilter (with the blue bulb on it) fits correctly into the prefilter container or once again detritus will bypass the prefilter through the openings where they are supposed to lock together - it is necessary to replace the top part occasionally as the tabs that lock into the bottom container go bad after a while. Bottom media basket you want to cut to fit sponge filter pads with medium on the bottom and fine on the top, the rest of the baskets should be filled with a sintered glass bio media. Don't waste your time with the carbon impregnated sponges, use the top half basket for carbon inside a fine media bag. Throw away the useless blue and orange sponges that come with unit.original review:I have both the 600 and 350, and they both do a great job. Overall the filtration is great and my aquarium water hasn't looked so good since before I installed these. Each basket will hold 1 liter of sintered glass bio media and the fine pre-filters do a good job of keeping the bio media clean. There are a couple of negatives too though. First, unless you first lock and remove the inlet/outlet tubing there is no way you can remove the pre-filter without spilling water because of the back pressure - something that is problematic in that I change out pre-filter cartridges daily (I have spares for each). About 25% of the time that I swap out the pre-filter on the 600 removing the tubes will result in a leak because I have to move the filter with the tubes disconnected to remove the pre-filter cartridge. Also, the filters are louder than I would like - not terrible, but louder than previous canister filters I've had. Having said all that, I'd recommend the Biomaster filters based on the massive amount of biomedia they hold, and their overall performance in keeping the tank clean and the fish happy.