<a href=showthread.php?s=&postid=8377430#post8377430 target=_blank>Originally posted</a> by sherm71tank
Al, you still with us? This is for YOU after all!
sherm71tank, yes, I'm still here trying to make heads or tails of all of this. I am still salivating at your picture of the 100 scfh beckett skimmer. I'm starting to wonder if the RC500 is the right skimmer for me after all.
One conclusion I'm coming to is that it seems no one really knows many of the answers here but a lot of people have opinions. Many of the opinions are reasonable and based on their experience. But it still feels a little like a bunch of blind men trying to describe an elephant.
One conclusion I'm drawing is that there are substantial differences between skimmers of a particular design due to the design and engineering prowess of the skimmer vendor. An very well engineered NW skimmer can be light years better than a poor knockoff of the same skimmer by a vendor that doesn't really understand the design. When I hear people say things like "I had a <insert type here> style skimmer and it kept overflowing so all of those skimmers are crap" it is certain that they aren't dealing with a well engineered product. I tried to head off that problem in this thread by trying to limit the discussion to only very well engineered skimmers from established vendors. No DIY (since I can't buy one for my tank) and only the cream of the crop. Of course I didn't stop to think that almost no one thinks that they have a poorly designed skimmer. They blame it on the type of skimmer and then are happy to tell everyone that some other type of skimmer is much better. It is difficult to gather much useful advice from those kinds of postings.
I will say that I am troubled by the recirc vs. circ issue. I had hoped to come up with a strategy based on objective measurements, with scfh as the #1 driver, that would let me evaluate different types of skimmers (again only looking at the cream of the crop). And I expressly ruled out, in my evaluation criteria, energy efficiency. I too am looking for effectiveness so I am happy to have the best skimmer at improving the quality of my water even if it takes another 100 watts (which is still in the noise compared to my lighting bill). But the recirc/circ is making it hard to make progress on my task. And as far as I can tell no one knows what the curves for bubble dwell time look like, other than there is some assumption that 90-120 seconds will work well. Here's some more things that I don't understand yet:
- Take identical beckett skimmers like the Austin Oceans/Barr skimmers. A single beckett version does 45 scfh and has a bubble dwell time of X. Add the second beckett to the same skimmer and now the skimmer does 90 scfh and presumably does X/2 for bubble dwell time. I think the dual beckett will do a better job skimming my tank than the single beckett. I think you should be able to collect the data on these 2 skimmers and develop an algorithm that at least comes close to describing their comparable performance. But the more recirc argument is better prevents that.
- My current pick skimmer is the Euroreef RC500 with the new impeller. ER recommends 1-1.5x turnover through the skimmer. I have confirmed with ER that they still recommend that rate. I have a pump that will do 1.5X. But it sounds like there is a group that thinks that decreasing my turnover to less than 1X will result in better skimming. But if less than 300 gph is better, does that mean 200 gph is even better? How about 100gph? Even better yet? How about 1 gph? Is that still better than my 450 gph (1.5X) turnover? Unless I missed it, no one can point to any research or hard data to show this. Even the ER guys declined to tell me how they determined that 1-1.5X is best, although they stick with those numbers. So even if I'm trying to choose between needlewheel skimmers there is these very conflicting opinions as to what works better. And trying to rationalize beckett and NW performance looks even harder.
The good news is that as long as I stick to my "cream of the crop" list I probably will have good results no matter which skimmer I choose. I just wish there was more objective evidence and more hard data available to help.
I did ask the Austin Oceans guys why they can't do the 100 scfh that sherm71tank is getting and they confirmed that you have do up your airflow lines to 3/8" rather than 1/4". I have encouraged them to switch to 3/8" airflow lines. Seems like a pretty cheap way to double your scfh and they say their skimmer can handle the increased airflow. If they do that maybe I'll move back from NW to becketts...
Al
I wish Barr stuff was more readily available...
Actually, I have tested it, as the chart at the beginning of this thread shows. The truth is, that skimmer is designed to run optimally with the supplied valves almost wide open. That 1/4" line is on purpose, to partially restrict the air flow as a Beckett makes smaller bubbles when it is held back a little. With years of testing, my opinion is that running 45scfh each is the sweet spot, hence the design. However all units have dual air ports per injector, so you could run another line and double that 45 SCFH if desired. Or remove the air lines completely, and run wide-open, which would be over 100 SCFH, but loud.
