Write-Up Wednesday: The Recirculating Protein Skimmer


A protein skimmer provides mechanical filtration by removing organic molecules from your saltwater aquarium’s water. And a  recirculating protein skimmer differs from other protein skimmers in 2 main areas:

– the water depth required for the skimmer to operate

– the number of pumps that run the skimmer

Water Depth

Non-recirculating protein skimmers have to be run inside of your sump or tank and they all require a specific water depth to operate. (The exception is hang-on back protein skimmers which hang on the back of your tank or sump). Usually there is an acceptable range between 7-9″ (18-22 cm). Recirculating protein skimmers, however, do not require a certain water depth to operate and can be run external to the sump if need be.

Operating Pumps

A Hydor 2005 protein skimmer

A Hydor 2005 protein skimmer

On a recirculating skimmer, one or more pumps recirculate water inside the protein skimmer body while mixing the recirculated water with air. A separate pump feeds the protein skimmer body water. Contrast this with a non-recirculating protein skimmer where one pump feeds the skimmer water, mixes the air with the water and pushes water throughout the protein skimmer body.

Since the recirculating pumps only jobs are to recirculate water throughout the skimmer body as well as mix air into this water, the idea is that a recirculating protein skimmer is better at removing waste. Having owned both recirculating and non-recirculating skimmer, my experience is that the difference is negligible. Both my recirculating and non-recirculating skimmer performed well and the performance differences between them would be hard to attribute to the fact that one was or wasn’t a recirculating skimmer.

If you go the recirculating protein skimmer route, a quality recirculating skimmer will work well for your tank.

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Comments for this article (9)

  • Les branham says:

    On your site, I always see a lot of things that I want. What I don’t understand is why do you have things with a lot of moving parts that have the potential to fail. I have a life reef protein skimmer and I can place it in the sump or hang it off my tank. It has 1 pump and 1 adjustment knob. I set it and forget it. Every now and then I empty it. I guess my question is, why do you not support life reef equipment? Too expensive or too easy to maintain? The way I see it is that if you really want it to keep it simple with next to no maintenance, then life reef is the way to go. Even though it is expensive it will pay for itself quickly because it is maintenance free and so many options.

  • Will says:

    I think life reef needs a marketing director and a new website. First I’ve heard of them–and I don’t see what makes them special.

    That said…good tip. I’ve also had both, and I concur. The nice thing about switching away from the recirculating is my sump has more room now.

  • Dan says:

    The fact that life reef does not have a marketing director is the reason why i buy all of my equipment from them…. I only want stuff that works, not hype, IMO it’s more expensive buy hype, be disappointed, toss it in the garbage and then buy a life reef product. That being said i respect Mark and his opinions i enjoy his reviews on equipment whatever the brand, I would not want him to promote a brand over any other… Unfortunately life reef does not make everything i need.

    FYI I don’t work for Life Reef i’m just satisfied a customer, i have over 1000 gals and like to buy things once.

  • To Les…
    Les, thank you for your “marketing” my Lifereef! Only a true user of products can speak about their real performance, whereas a marketing director is paid to write words to make products sound great, often better than the product really works.

    To Will…
    Will, I’ve been making reef filtration since 1984 when the wet/dry filter was introduced to the U.S. hobbyist. The industry didn’t take off until 1989, 5 years for the U.S. hobbyist to accept the cost of doing a reef aquarium. My “marketing” is my customers. My website is old, I agree, but I have had a backlog of sump builds for the past 26 years, currently my sump schedule is seven months. That alone speaks highly for what customers will wait for, quality. In fact, more than 90 percent of my customers are those not happy with the mass-produced-mass-marketed stuff.

    To Dan…
    Thanks Dan for “marketing” my products via a satisfied user!

  • Dave says:

    I have Both types from the same manufacturer. One on a 93g one on a120g the only difference I really notice from the 2 is the recirculating type is less likely to inexplicably puke skimmer goo all over. But that is the reason I only run in sump skimmers regardless of style, because nothing makes your wife happier then NOT having a wet stinky floor.

  • Pierre Bouic says:

    I’ve got a hang on back of glass skimmer by Hydor and it works well , even though its not my primary skimmer I like to run several types to get the waste that one that’s not collecting presently misses.
    I was using 3 at once, one a counter circulation, a back pack filter with skimming chamber, and the most used in the hobby with the pin wheel air venturi and all collect well but when one isn’t collecting usually another is which is good. Each is fitted in a different locality, one on the rear of the display tank, one in the weir, and last in between the refuge.
    But I’m not into new equipment based on the latest fads.

  • Jim says:

    Anyone know where I can get a Life Reef bumper sticker??
    I too am a Life Reefer. Jeff builds it him self, when he has time, the way he has decided it works best. If you use it the way he intended, you can’t go wrong.

    The difference with Life Reef is the lack of trying to sell it to you to sell more, and letting you find it from him thru the folks who are happy with what he has done for them. Products speak for them selves. Anyone who is looking for a piece of reef equipment should do some research on the product they are looking for. The things i read about his products that made me try them, i found to be true. The packing for shipping is just amazing. The products hold up to daily use. There easy to set up. They come with everything you need. and they work exceptionally well the way he has designed them. I have made no modifications to what i have and I’m a modify it sort of guy. All my “other “stuff is drill, glued, clamped, adjusted, tied back, and fussed with to get it to perform the way I was lead to believe it would work for me. But My Life reef stuff worked out of the box better than i can figured how to change it. I just use it and enjoy my 2 yr old 100G Mixed reef.

    Jeff has innovation, simplicity, reliability, experience, and quality that is not often matched in any other manufactures products all at once. I simply trust him to provide me with what i will need to be successful. He does it for a living because he knows how.

    Great write up on recirc skimmers MARK and as always we appreciate your efforts advancing the Hobby. Happy reef keeping everyone.

  • Richard says:

    Come on folks, this article was about skimmer types, not brands. The only information important about this article is the difference between types and how they work.

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