moore030 November 20, 2007 Share November 20, 2007 It seems to me that the main difference is that the recirc pump sucks water from inside the skimmer with a relatively small feed from the sump, but the regular skimmer sucks all its water from the sump. The water from the sump is dirtier than the water in the skimmer, so it looks like you would get the most cleaning power per watt by using the dirtier water. ? Brett Link to comment Share on other sites More sharing options...
Brian Ward November 20, 2007 Share November 20, 2007 It seems to me that the main difference is that the recirc pump sucks water from inside the skimmer with a relatively small feed from the sump, but the regular skimmer sucks all its water from the sump. The water from the sump is dirtier than the water in the skimmer, so it looks like you would get the most cleaning power per watt by using the dirtier water. ? Brett Increased contact time, more gunk removed from the water, cleaner water returned to the tank Link to comment Share on other sites More sharing options...
extreme_tooth_decay November 20, 2007 Share November 20, 2007 Increased contact time, more gunk removed from the water, cleaner water returned to the tank That's the party line, and it makes sense...but I'd sure like to see some real stats. Something along the lines of: After the recirc mod, my skimmate got 3 shades darker or After the recirc mod, I collected .25 liter more skimmer per day than before or After the recirc mod, my wife left me because the skimmate stunk so much worse or After the recirc mod, I had to lower my riser tube 2" because of how much more I was getting Without stats like this, it's a little weak, even though it conceptually makes sense, it may in the end not really do much. tim Link to comment Share on other sites More sharing options...
moore030 November 20, 2007 Author Share November 20, 2007 If each skimmer is making the same amount and size of bubbles then each would have the same contact time (is that right?), but the water inside the skimmer is cleaner (because it is recirculating) than the water coming in from the sump. So it still seems to me like the non-circ skimmer would be pulling out more stuff. Link to comment Share on other sites More sharing options...
BeltwayBandit November 20, 2007 Share November 20, 2007 I think Tim hit the nail on the head. There is a lack of empirical data comparing the two methods. The contact time, if I have this correctly, is the amount of time a specific volume of water remains in the skimmer chamber and exposed to the microbubbles. In a regular skimmer the net flow through the skimmer is higher than that of a recirculating skimmer, therefore it has a lower 'contact time' than the recirc. So you end up with: recirc: less volume cleaned per hour, but returns cleaner water to the system standard: higher volume cleaned, but returns less clean water to the system A test that I would like to see is have identical 'organic loads' placed on a recirc and a nonrecirc skimmer. Run them for a set period of time and then measure the resulting 'organic load' in the system. My gut feeling is you will initially get a quicker knockdown of the 'organic load' with a nonrecirc skimmer because you move more of the water volume per time through the skimmer but that over time the recirc skimmer will settle out at a lower 'organic load' because it is capable of greater organic removal. This is just my assumption based on knowledge of how each skimmer works. Link to comment Share on other sites More sharing options...
lanman November 20, 2007 Share November 20, 2007 My gut feeling is you will initially get a quicker knockdown of the 'organic load' with a nonrecirc skimmer because you move more of the water volume per time through the skimmer but that over time the recirc skimmer will settle out at a lower 'organic load' because it is capable of greater organic removal. This is just my assumption based on knowledge of how each skimmer works. I agree - that makes sense to me. And after running my skimmer for a few weeks, it pulled less... and less... and less... stuff out of the water per day. So - by the time you get to the point where your water is 'very clean' - I think the recirculating skimmer will get it 'even cleaner', and the non- recirc skimmer will stay at 'very clean'. (Forgive all the scientific terms...) bob Link to comment Share on other sites More sharing options...
moore030 November 21, 2007 Author Share November 21, 2007 Well, it looks like there's not an obvious answer at any rate. A cool thing about recirc IMO is that "bubble making" is a separate system from "water moving." That gives a chance to take advantage of the natural flow of water from the main tank to sump. Although I'm not sure that would make alot of difference... Link to comment Share on other sites More sharing options...
jamesbuf November 21, 2007 Share November 21, 2007 Considering that all the major brands have switched to recirc pumps, and I'm sure they've done waaaaaaayyyyyy more testing than we can fathom, I think we can all rest assured that the recirc pumps are the way to go. Link to comment Share on other sites More sharing options...
flowerseller November 21, 2007 Share November 21, 2007 It all depends upon who you talk to and how much partying they've done. That's the great thing about this hobby. Then you take those DIY Bozo's like me who are still bumping along with a 15yr high volume down draft skimmer. Back in my day, I didn't miss many parties either. Link to comment Share on other sites More sharing options...
extreme_tooth_decay November 21, 2007 Share November 21, 2007 Considering that all the major brands have switched to recirc pumps, and I'm sure they've done waaaaaaayyyyyy more testing than we can fathom, I think we can all rest assured that the recirc pumps are the way to go. No offense, but that's just the kind of argument that is prolific in this hobby and I find very frustrating. If they have data, let's see it. Why would they hide it? I for one am not the least bit convinced they have it...or if they do have it...maybe the reason they aren't coming forward with it is because it won't help them sell recirc skimmers...bottom line is without data, we are all guessing. tim Link to comment Share on other sites More sharing options...
ArtC November 21, 2007 Share November 21, 2007 Considering that all the major brands have switched to recirc pumps, and I'm sure they've done waaaaaaayyyyyy more testing than we can fathom, I think we can all rest assured that the recirc pumps are the way to go. In my other fish hobby, they say lures are designed to catch fishermen, not fish. The fact that the major brands sell them is evidence that they sell better, not that they work better. This statement does not imply that I have a position on the technical issue. Link to comment Share on other sites More sharing options...
jamesbuf November 21, 2007 Share November 21, 2007 Well when I recirced both my pumps on my old ASM G5, my zoanthids were literally stuck on pause and there was no noticeable growth over a several month span, which I attributed to the increased crud the skimmer was pulling out of the water. All at the same time that my sps exploded, again because the water was cleaner. That is what convinced me to never own a non-recirced skimmer again. Not to mention I had less crap (snail shells, etc) get stuck in my needlewheel since it wasn't the feed pump for the skimmer. The first time I cleaned the Sedra pumps, I pulled out over a dozen baby snail shells from each needlewheel. I fed the skimmer with a Maxijet with the grate on it so no inverts, or other life, made their way into the skimmer body. Yet another advantage of not using the needlewheel as the feed pump. Hope this helps. Link to comment Share on other sites More sharing options...
ArtC November 21, 2007 Share November 21, 2007 http://en.wikipedia.org/wiki/Protein_skimmer Reference 1 in the wikipedia article is 'the' technical reference on skimmer design. At least whenever I've seen a reference to engineering a skimmer, this has been the reference. Don't know if it manages to differentiate the Navier-Stokes equations to define the optimal skimmer. Link to comment Share on other sites More sharing options...
jamesbuf November 21, 2007 Share November 21, 2007 In an industry where this is so much money at stake by having a better, more effecient product, you're trying to tell me they don't extensively test their products? Come on. Well when I recirced both my pumps on my old ASM G5, my zoanthids were literally stuck on pause and there was no noticeable growth over a several month span, which I attributed to the increased crud the skimmer was pulling out of the water. All at the same time that my sps exploded, again because the water was cleaner. That is what convinced me to never own a non-recirced skimmer again. Not to mention I had less crap (snail shells, etc) get stuck in my needlewheel since it wasn't the feed pump for the skimmer. The first time I cleaned the Sedra pumps, I pulled out over a dozen baby snail shells from each needlewheel. I wonder how much his cut down on efficiency?? I fed the newly recirced skimmer with a Maxijet with the grate on it so no inverts, or other life, made their way into the skimmer body. The next time I cleaned the pumps there was nothing stuck inside the needlewheel. Yet another advantage of not using the needlewheel as the feed pump. Hope this helps. Link to comment Share on other sites More sharing options...
Carl November 21, 2007 Share November 21, 2007 http://reefkeeping.com/issues/2002-06/fm/feature/index.php Some background reading...may or may not answer your questions... Link to comment Share on other sites More sharing options...
extreme_tooth_decay November 21, 2007 Share November 21, 2007 (edited) In an industry where this is so much money at stake by having a better, more effecient product, you're trying to tell me they don't extensively test their products? Come on. If they did, and the results clearly showed recirc was better...they would be fools not to make the results public. The web should be dripping with all the hard evidence they have. Now if they did the testing and found recirc wasn't really better...but they sell better... As ArtC said, the big money at stake is for having a product people want more, not a product that catches more fish or skims more efficiently. tim Edited November 21, 2007 by extreme_tooth_decay Link to comment Share on other sites More sharing options...
dandy7200 November 21, 2007 Share November 21, 2007 Cloak and Dagger stuff here. Link to comment Share on other sites More sharing options...
flowerseller November 21, 2007 Share November 21, 2007 I think Tim hit the nail on the head. There is a lack of empirical data comparing the two methods. The contact time, if I have this correctly, is the amount of time a specific volume of water remains in the skimmer chamber and exposed to the microbubbles. In a regular skimmer the net flow through the skimmer is higher than that of a recirculating skimmer, therefore it has a lower 'contact time' than the recirc. So you end up with: recirc: less volume cleaned per hour, but returns cleaner water to the system standard: higher volume cleaned, but returns less clean water to the system A test that I would like to see is have identical 'organic loads' placed on a recirc and a nonrecirc skimmer. Run them for a set period of time and then measure the resulting 'organic load' in the system. My gut feeling is you will initially get a quicker knockdown of the 'organic load' with a nonrecirc skimmer because you move more of the water volume per time through the skimmer but that over time the recirc skimmer will settle out at a lower 'organic load' because it is capable of greater organic removal. This is just my assumption based on knowledge of how each skimmer works. How come Craig always seems to make sense? Link to comment Share on other sites More sharing options...
jason the filter freak November 21, 2007 Share November 21, 2007 Cloak and Dagger stuff here. Can you not explain this? Also as a note resic skimmers are more efficent in terms of power consumption Link to comment Share on other sites More sharing options...
extreme_tooth_decay November 21, 2007 Share November 21, 2007 Can you not explain this? Also as a note resic skimmers are more efficent in terms of power consumption I would say they are less efficient. Typically, folks add a feed pump for recirc skimmers. Now you're running a whole extra pump: bigger bill, same result in skimmate cup... tim Link to comment Share on other sites More sharing options...
bigJPDC November 21, 2007 Share November 21, 2007 In an industry where this is so much money at stake by having a better, more effecient product, you're trying to tell me they don't extensively test their products? Come on. Is that why everything at PetSmart is of such high quality? I think you are forgetting that this is a niche hobby with very few competitors in terms of equipment, sorry. I thought that space for equipment dictated whether the skimmer goes in the sump or not. In my livingrooom setup I could never use a recirc. We have another one of those logic vs. emotion arguments here guys, and it's not going to get anywhere, again. ETD wants facts to back up a choice of technology, which may not exist. You'd have to set up identical tanks plus a control with the only difference (in every environmental variable) being the skimmer type - and then monitor for a significant length of time and then determine some criteria for measurement. And then do it ten more times to get your results. Or, just give it a shot and see if your zoos get bigger. James I wonder what would happen if you went back to the in-sump model and cleaned it more often - just think if they got bigger again. Link to comment Share on other sites More sharing options...
Rascal November 21, 2007 Share November 21, 2007 Now I wish I had waited longer before doing the recirc mod on my skimmer. I think Tim has a good point about wanting to see results in the cup. If you take an established tank with a non-recirc skimmer and then do the recirc mod on it and change nothing else, that would at least be something. Of course to be really scientific about it you couldn't just measure the amount of liquid in the cup because of differences in wet vs dry skimming. I think I remember an article once about dehydrating the skimmate and then weighing it to get an accurate measure of organics removed. Anyway, here's my very non-scientific take on why I think it was an improvement for my skimmer (ASM G4). First, the Sedra 9000 is rated at 900 gph, even figuring some reduction b/c of the needlewheel and head loss, I still thought it was way too much flow through the skimmer. The biggest advantage I could see though, was that it resulted in a huge increase in the amount and density of bubbles in the skimmer body. I guess this is partially related to having the slower flow through the skimmer, but I think it is also because that recirc is pulling in some water that already has bubbles in it, and then chopping those bubbles up into smaller bubbles while at the same time adding more bubbles. Whatever the reason, there was no question that I had more bubbles after the mod. So not only is there more contact time because the water remains in the skimmer longer, there are also more bubbles in the skimmer for the water to be in contact with. Link to comment Share on other sites More sharing options...
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