It seems the term 'closed loop', once considered by hobbyists (and still considered by anyone that has a vested interest in their system such as public aquariums, hatcheries, and aquaculture facilities) to be the ultimate form of random, turbulent water motion is slowly but surely losing popularity. This is too bad, because the internal pumps still have several drawbacks: harm to invertebrate life (think how many anemones have been shredded!), heat transfer, electrocution risk, inefficiency, and let's face it: they're ugly, and a giant pain to move around/adjust/clean. I feel that there are several reasons closed loops/dump buckets/other types of more 'quality' water motion have lost popularity in favor of these internal pumps, which I'd like to discuss individually.
Profit
Probably the largest driving factor is the dollar: these pumps are heavily advertised, and the aquarist is exposed to this form of water motion more than any other, simply because the manufacturer's want you to buy them - and they are quite a bit more costly than a few feet of PVC and a single external pump! For a few hundred a month, any aquarium blog or forum will tout the 'benefits' of these pumps, making it extremely easy for manufacturers to inundate our niche hobby's market (see that Vortech or Tunze ad on all of the aquarium sites you frequent...?).
Probably the largest driving factor is the dollar: these pumps are heavily advertised, and the aquarist is exposed to this form of water motion more than any other, simply because the manufacturer's want you to buy them - and they are quite a bit more costly than a few feet of PVC and a single external pump! For a few hundred a month, any aquarium blog or forum will tout the 'benefits' of these pumps, making it extremely easy for manufacturers to inundate our niche hobby's market (see that Vortech or Tunze ad on all of the aquarium sites you frequent...?).
Design Flaw(s) in the Aquarium
Many, if not most reef aquariums, large and nano, are ill designed from the start. While water motion has been proven to be the most important factor in the health and growth of corals, it is usually treated as an afterthought. Proper plumbing, returns, overflows, or manifolds are rarely installed, although the benefit of closed loops is great. In addition, many all-in-one aquariums, even those designed to be nano-reefs, offer sub-par water motion and very little ways to remedy this. It is my opinion that a system that requires the addition of an internal pump to aid circulation is a system with a major design flaw. There is a reason that every single public aquarium, aquaculture facility, hatchery, and propagation system uses a closed loop method of water circulation, and I've worked with or consulted for several!
Many, if not most reef aquariums, large and nano, are ill designed from the start. While water motion has been proven to be the most important factor in the health and growth of corals, it is usually treated as an afterthought. Proper plumbing, returns, overflows, or manifolds are rarely installed, although the benefit of closed loops is great. In addition, many all-in-one aquariums, even those designed to be nano-reefs, offer sub-par water motion and very little ways to remedy this. It is my opinion that a system that requires the addition of an internal pump to aid circulation is a system with a major design flaw. There is a reason that every single public aquarium, aquaculture facility, hatchery, and propagation system uses a closed loop method of water circulation, and I've worked with or consulted for several!
The superiority of the closed loop manifold is virtually unsurpassed - A. Calfo image
Convenience
I hear this one a lot, although I don't see it. Apparently it's "easy" to stick in a bunch of large, ugly pumps, plug them all in, adjust them all up-to-the-elbows in saltwater, and then slowly watch them clog from algae and other material so that the aquarists is forced to remove, clean, and re-install the pumps every few months. Personally, I don't see any convenience here, but this is subjective.
Price
Granted, the Koralia pumps are fairly inexpensive per unit, but the Vortech certainly isn't, nor are the Polario models from Rio or various models from Tunze. Plus, more than one unit is needed for most aquariums. The cost of PVC for returns and/or manifolds is very cheap, and a single, quality external pump will usually cost less than one Vortech internal pump. Not to mention that manifold returns are very easy to adjust, distribute water much better than any prop pump can (regardless of hype), are of no risk to motile invertebrates, and consume less power per gallon moved.
When I design and install a saltwater or reef aquarium for a client, I ensure that I do not need to use any in-tank pumps for water motion. Closed loops are more reliable, provide a more turbulent water flow, are much less unsightly, require much less maintenance, and are overall a much better option. While certainly better that powerheads, the hype associated with prop-style pumps is undeserved. Superior, and cheaper, methods of turbulent random flow existed long before, and still continue to be superior to, prop pumps. Do your aquarium a favor and put real thought into water motion!
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The ignorance and lack of understanding about water flow in this entry is appalling. Closed loops have their place but what Calfo concocted is nothing like a closed loop. Including that illustration is the cherry on top of this parody of an article. I implore you to remove or seriously revise this blog entry.
Posted by: jake adams | 06/01/2010 at 11:07 AM
I find this comment amusing, especially from someone who is basically a "front" for the aquarium product industry, and who's site is sponsored by EcoTech Marine AND Hydor. If you have a specific issue with the post, please address that - a blanket statement of "appalling ignorance" or "you're wrong just because I say so" doesn't help anyone learn anything, which is the main purpose of this blog.
If you'll notice, I initially put the term "closed loop" in quotations, because although it refers to a specific design in plumbing terms, in the world of aquarium jargon that is not necessarily so, as you should know. The picture illustrates the basic concept of a Calfo closed loop manifold, a very simple and effective method for reef aquarium water movement in home aquariums, which is what this post is discussing. It's not the only way, and arguably not the best way, but it beats the heck out of a half dozen prop pumps stuck inside a tank.
The point of this post is to encourage aquarists to move away from in-tank pumps. Anyone touting that putting big cages around propellers in an aquarium is a superior method of water motion than a pre-plumbed, multi-directional water return system with a central pump is badly misinformed, or lacks experience, and I noticed you didn't disagree with that - and of course, public aquariums and other professional systems almost always use closed loop style circulation.
I believe you said it best in your Advanced Aquarist series: "use modest equipment to produce adequate water flow".
Posted by: Captive Aquatics | 06/01/2010 at 03:03 PM
Hey I see what you're getting at here - I've got a couple of Koralia pumps in my 75 gallon fish only setup, and they've been working pretty good for me, but I'm increasingly getting interested in a closed loop style of water pump system. I don't really have too much of a problem with the pumps getting gunked up and stuff though, they've been running maintenance free for about a year.
The only problem with my setup is I just really might not have enough room to add something like this, my aquarium is in some pretty tight quarters haha, but if I used some thinner plumbing and made it as form-fitting as I possibly could, moreso than some of the other examples I see online, I might be able to make it work without being too cumbersome for my situation.
Posted by: Luke | 07/23/2010 at 10:09 AM
Just like Jake I too am interested in setting up a closed loop styled system but I too am inhibited by a lack of space. Just trying to see if there's a work around that I could use.
Posted by: Fish Tank Filters | 07/28/2010 at 10:54 PM