Skimming Principles

<a href=showthread.php?s=&postid=6436779#post6436779 target=_blank>Originally posted</a> by BeanAnimal
So the skimmer is sitting in a sump in case it overflows?
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Yes and No. As a risk mitigation I decided to run my skimmer in the sump. If anything leaks or fails, it will just feed back to where I want it anyway. I had the space in the sump anyway.

I do not know if the extra fine stones would work correctly? I assume that if your compressor could overcome the back pressure they would.

Crazzy, I am not sure what you mean by your question on skimmer height. My fine pore stones produce bubbles ranging in size from micro bubbles to average small bubbles. Aquatic eco says they will produce .5 - 2 mm bubbles. I would guess that my stones are actually in that range. So skimmer height all depends on which bubbles you want to entrain. Water flow does have an effect on the bubble dwell. On the smaller bubble it has a a significant effect. In fact my water flow calculations look promising within the accuracy of my tools and equipment.

Dale
 
well ok.. if you wanted all bubbles to remain for 2 min in a fluid state, this would reduce the build up and reduce cleaning of a skimmer, make it extremely efficient, and remove all trace elements. if some of the bubbles were traveling for more than two min and others for 15 seconds then you would achieve great results but still have a skimmer than would need to be cleaned so that when the bubbles do collect the material that they would not break in removal process... on another note a wet neck... does this actually add to the dwell time?
 
Wet Neck does not add to dwell. If anything it reduces it by allowing the foam to travel up the riser faster. That is not necessarily a bad thing though. Since friction is reduced, you have a cleaner neck with less bubble loss.
 
I wonder if a skimmer with Escobal's parameters, except at one turnover every hour, as opposed to one every 12 hours... would corals die of starvation after a few years/months? Anyone have instances they remeber hearing about, with actual results of this? I'm talking about massive/overkill amounts of skimming. I'm just wondering about the merits of overskimming vs. underskimming. It would be good to test the extremes of skimming, for example. One of these extremes has already been tested, of course....

G1
 
I don't think there is any such thing as "over-skimming". The skimmer can only skim what impurities are presented by the tank. If you feed more, you can get more skimmate, etc. but if there are low impurities, you will get a small amount of skimmate. That's why skimmers tend to get a lot of gunk when first installed but it tapers off later on.

IMO much of the tank size rating for skimmers is just bull. Although there can be some size issue like putting a small HOB on my tank wouldn't have good net results, but skimming results are related to tank inhabitants and and maintainance just as much if not more than tank size.
 
<a href=showthread.php?s=&postid=6458146#post6458146 target=_blank>Originally posted</a> by jnarowe

IMO much of the tank size rating for skimmers is just bull. Although there can be some size issue like putting a small HOB on my tank wouldn't have good net results, but skimming results are related to tank inhabitants and and maintainance just as much if not more than tank size.
Click to expand...

I both agree and disagree with that statement. I believe that many of the skimmers on the market are not really capable of skimming the tank size they claim. Skimmer size really comes down to turnover rate. How much water do you have to skim in a given peroid of time.

For me, if I use the principals of Escobal, I need to skim at 2 GPM. For Jonathons tank, it is closer to 20 GPM. Now that you know the feed rate, pick a skimmer that will yield adequate operation with those conditions. Normal skimmers for the average hobbiest would not give very good dwell time for a 20 GPM feed.

Dale
 
Well, in my case we aren't really talking about "normal" anyway, but your statement leaves the door wide open when you state "IF I use the principals of Escobal". "If" is a big IF!

If I have a lot of live rock. If I have a lot of tank cleaners. If I have a bare bottom. If I have a refugium. If I have a remote DSB. If I have 1 fish per 50 gals. If I have a rigorous maintainance schedule. We can go on-and-on with the IFs...

My assumption is that skimming is just one part of the tank cleaning process,and that a well rounded approach to a captive habitat will far out-weigh the best skimmer that can be built. I don't mean this in any argumentative way either and your data and practical results will be very useful to anyone who wishes to keep a reef tank. Most importantly, it will help people who are planning on buying a ready-made skimmer because they will be able to look at the design and make a much more informed purchasing decision. For DIY types like you and me, we can build a skimmer and see how it goes. If we want more skimming, we can build another one or add another one.

What I don't see in any reference material is how we can judge whether we are skimming enough or "too much". What measurement can we take? None really other than observing our system and determining whether improvement is neccessary.
 
I guess the test system might come from somebody who has a large tank and a nano, and for some reason used the big skimmer from the large tank (maybe shut it down for some reason), and put in on the nano. There is of course the argument that the long term health of corals is dictated to some degree by the presence of zooplankton, like rotifers or something. I really have no idea what the numbers might be. With zero plankton, corals might run into health problems after awhile. I guess that's not the point of this thread though. Good discussion though. These skimmer threads are really interesting to me. Lots of new points that I never thought of. Keep it up...
G1
 
And you bring up the most interesting and puzzling thing for me: Many of the very best looking reef systems, and particularly SPS systems, have extremely low nutrient levels. They are highly skimmed, refugium scrubbed, treated with UV, and have other filtration as well. You can barely see the water if at all.

This doesn't quite match what I have seen in the wild. In fact when I originally set out to start a captive reef, I really envisioned a bit more murky environment. It's not just eye candy to me. I am looking to create as natural of an eco-system as I can. I realize that's somehwhat of an impractical dream, but I think in many ways it can be and has been acheived by others.
 
jnarowe I think the thing we have to remember is that thre are a lot of differences between our captive environment and the real reef. Things that occur in nature may not be doable in our systems. The reality is that we may have to do things rather different to sustain life. This includes nutrients, lighting, wave motion etc. The only thing you can do is try, and track your results and weight them against your expectations or desires.

Bean
 
you can remove all trace elements if bubble dwell is over 120 seconds, this combined with a correct turn over will remove even trace metals.
 
I dunno.. he has popped in here a few times and commented, but I can't ever quite follow what the post is saying or is in reference to. It may well be that the crazzyreefer is just living up to his name!

In all honesty I think he is trying to convery information regarding the title of this thread. A skimmer of sufficient height and correct turnover should remove everything that is removable, for lack of better words.
 
I can tell you my skimmer fell far short of the 120 second bubble. I can also tell you that my bubbles do not rise at 3 cm/s as was originally stated by Crazzyreefer. He based that report on the paper he linked to. When I read the paper, I got something like 30 cm/s from it. I questioned it, but was assured that his numbers were based on fact. So I worked on my skimmers bubbles. I questioned him in a earlier post about this, but it was never answered. I was just trying to understand how he interpreted that number. Unless it was a case of a misplaced decimal point ( 30.0 vs 3.00 cm/s).

The reality I have found, is even my microbubbles rise faster than that. I would love to have a skimmer full of microbubbles, but I have yet to see that quantity of them from any skimmer air source.

In any case, I have my skimmer and it is working. I may change the riser setup.

Dale
 
Great to hear Dale. I have seen large beckett skimmers completely filled with micro-bubbles, but they are running on huge pumps.
 
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