Skimmer Ratings- a discussion.

[Powerman]

Here's the thing... No matter how big or bad your skimmer is you can never pull more than 30% of the docs out... I have a post somewhere around here were there was article from advanced aquarist on the subject... The game is more of who can remove those 30% the fastest... Hence the reason we cant over skim!!!!!!!

My only problem with it is.....and they even raised the questions themselves.... that is only 30% of total organics. Not all those organics are hydrophobic and will never be removed by a bubble. What I want to know is of the percent of hydrophobic organics removed, and what is the threshhold the skimmer will remove. If a skimmer can only remove 75% of total hydrophobic organics, then why the 75%?

The question you mention about over skimming, what is the threshhold based on... an amount or a concentration to water and is that concentration based on skimmer performance or by water preperties with very little hydrophobic organics?

I really liked those studies, but it raises more questions than it answers. Certainly a step in the right direction though.

 

[luke33]

That test was a great effort, but imo not done very well. The 30% reminds me of the 2 min dwell time theory.

 

[hawaiireef]

does anyone have the link to that article?

This article, while not on the topic of skimming but rather DSBs, is the sort of research that can really move our hobby forward, and imo we need re: that profit center called "skimmers": ScienceDirect - Aquaculture : An experimental comparison of sediment-based biological filtration designs for recirculating aquarium systems

 

[hawaiireef]

check out the results of this article: Feature Article: Further Studies on Protein Skimmer Performance | Advanced Aquarist's Online Magazine, which I think tend to support a 2 stage approach. the skimmers that removed TOCs the fastest, were not the ones that removed the highest percentage of TOCs over time. 2 stage, with different design for each stage, could offer the best of both worlds. Or the idea to use 2 skimmers, one maximized for rate of TOC removal, the second for total percentage of TOC removal over time. it would be nice to know which design factors are recponsible for "high flow" versus "efficient" skimmers.

 

[Powerman]

Well that's the article we mentioned, there is a first part too. However, I don't follow how that study supports a foundation for multi stage skimming.

And that is one of the problems with the study. Total dissolved organics contain many compounds. Some hydrophobic, some hydrophilic. Just like carbon, one pore size does not remove all compounds. A skimmer is not going to remove hydrophilic compounds. So what percentage the TOC philic/phobic concentration matters. Nor does any type of wave action remove hydrophilic compounds in the ocean.

So all skimmers removed the cow poop they through in, and some removed it faster than others, yet the study basically concludes that since skimmers only removed 30% TOC, then they are about as useful as paper weights at removing DOCs.

Now I'm not trying to get off on a rant about that, I just said that to explain how I don't get how you feel multi stage skimming is possibly an improvement based on that study.

 

[hawaiireef]

because the skimmers with the fastest rate of TOC removal were not the ones with the highest overall percentage of TOC removal. and yes, I get that not all TOCs are removed by skimming, but there is also a significant variation in percent removed, from the "top rated" (by speed of removal) ES 100 (@24% removed) to the "bottom rated" (by speed of removal) Bubble King (@37% removed). So it would seem to me that a 2 stage skimmer could be made to optimize for speed (first stage) and total % removed (second stage).

Regardless, what would be particularly interesting and relevant, is why skimmers (what design elements) seem either optimized for one or the other variable. I think that you will find neck diameter is right up there, and wider may not necessarily be better.

 

[Powerman]

because the skimmers with the fastest rate of TOC removal were not the ones with the highest overall percentage of TOC removal. and yes, I get that not all TOCs are removed by skimming, but there is also a significant variation in percent removed, from the "top rated" (by speed of removal) ES 100 (@24% removed) to the "bottom rated" (by speed of removal) Bubble King (@37% removed). So it would seem to me that a 2 stage skimmer could be made to optimize for speed (first stage) and total % removed (second stage).

Regardless, what would be particularly interesting and relevant, is why skimmers (what design elements) seem either optimized for one or the other variable. I think that you will find neck diameter is right up there, and wider may not necessarily be better.

Got it..... Drawing from that you could say 2 stage... 1st stage being high throughput low air could remove faster... and then more efficient higher air skimmers would do the rest. The problem is that once you change the organics from the first stage, it does not mean the 2nd stage would work the same. Yuo could very well be nuetering the second stage and end up with less organic removal overall.

One conclusion drawn could be that the BK removed the most overall, which is what you want...over time what does the best. That if you have a well rated skimmer, say the BK160 on a 90g, then overall performance is better, and that since you have some head room speed of removal does nor matter as much.

And yes they are good questions. Like I said, I don't think the study is the end all be all answer to the question, but a good start and is directly relevant to the conversation of skimmer ratings and performance. In the end, any discussion on what is best for nutrient reduction and cleaner water is a good discussion to have. you would think GAC could remove more and that instead of skimmers we just used big carbon filters and spent a bunch on carbon. But gAC has been used forever and has not been found to be the magic bullet for clean water. We all know we can run skimmer less if we did 50% WCs weekly. :bigsmile:

 

[Powerman]

So I wanted to bring this back to discuss ratings of older skimmers. Seems some respected skimmers of dated designs have some pretty high ratings compared to numbers today. Some skimmers I've seen are rated up to 220g pulling just 600 lph of air. With todays skimmers that seems to be low air draw. Yet they older ones do have bigger reaction chambers.

For example Deltec. No bubble plate but bigger body. Reted for 220g heavily stocked with 600 lph of air. Compared to todays numbers that seems odd. There are others the same... like ASM.

 

[mojo]

Its not all about air draw too. Alot has to do with water through put more than just air. I think more and more people today find themselves with too larger of a skimmer and inconsistant performance.

 

[Powerman]

I have come across other examples, but just recently was looking at a Deltec AP851. It does 600 lph of air and 1000 lph (220g) of water. Has a 7.8 inch body with 3.5 inch neck. I do realize water through put is important, but that stat is not redily published by many makers and I have yet to come across any sort of range to be in as far as system volume turnover.

That would compare to some skimmers today in the 100-150g range yet it is rated up to 220g. I only bring it up because Deltec is respected. Not necessarily trying to pick on a single skimmer, but with many of the older skimmer the story is the same.

My only point is to bring up trends of newer skimmers and what they can do. Are they over/under rated? Do older skimmers have longer bodies to help? Are newer skimmers improving and refining the product or are these just the latest greatest fad to jump on.

 

[mojo]

Some fad some good design, I know some makers will rate there product the same as a competitor because they dont want to feel like there product is inferior. The sicce pump for example. Used on a lot of popular skimmers. Most rated for over 200 gallon tanks.
Sorry this pump does not turn over enough water to skim a tank that size. no matter how much air you can pull with it, its not going to skim enough to keep up with a load of a 200+ gallon tank. I would say 150g max for a sicce. again this is just an example. But I think a lot has to do with theory and what ever can get sales. I would stick to what is tried and true. what works, has great service and is easy to use. What more can I say.

Mojo~

 

[ginak_27]

Hello,

First off I found this discussion just googling and researching what are the best skimmer's out there and what I would need for my particular setup. I am amazed and wowed. I read this whole entire discussion and actually am feeling like I have a better understanding of how they work and what factor's to consider and oh my goodness how important they actually are!!
I have read this to my husband as well who is off reading a book we purchased at the Birch Aquarim in La Jolla, Ca. You see we have started maintaining a salt water aquarium about 2 years ago, It was a14gallon biocube. Those days are over and we have transfered to a 60 gallon. We are in the beginning stages of setting up and what to buy a really good protein skimmer that will suit our setup. So with all over your knowledge and experience can I ask this question... what would actually work best for our 60 gallon reef tank? I almost feel dumb asking this because I feel now I might actually have a idea what to look for... but seeing that you all have years of experience I would Love to get your input? Thank you so much!

 

[lvsuckerfish]

wow this was a good read I do understand skimmers and how and why they are rated the way they are.

 

[Troylee]

Hello,

First off I found this discussion just googling and researching what are the best skimmer's out there and what I would need for my particular setup. I am amazed and wowed. I read this whole entire discussion and actually am feeling like I have a better understanding of how they work and what factor's to consider and oh my goodness how important they actually are!!
I have read this to my husband as well who is off reading a book we purchased at the Birch Aquarim in La Jolla, Ca. You see we have started maintaining a salt water aquarium about 2 years ago, It was a14gallon biocube. Those days are over and we have transfered to a 60 gallon. We are in the beginning stages of setting up and what to buy a really good protein skimmer that will suit our setup. So with all over your knowledge and experience can I ask this question... what would actually work best for our 60 gallon reef tank? I almost feel dumb asking this because I feel now I might actually have a idea what to look for... but seeing that you all have years of experience I would Love to get your input? Thank you so much!

I would roll with a bubble magus nac6 personally...

 

[lvsuckerfish]

OK I want some insight on this,

if you have a skimmer say a h2 on a 70gal system total volume will this skimmer be considered over skimming?

This is the way I look at it, if the skimmer is way to big for the system. I would not see over skimming as the foam head would not hit the collection cup but only so many times, the organics would be in the body and that is where we see alot of waste build up on the lower portion of the neck and upper portion of the body. But when the organics levels did raise high enough to build up a good head of foam then the skimmer still would only take out so much!

I think it is impossible to over skim if the skimmer is not functioning like it is supposed to?