Wet Foam vs. Dry Foam

[tankgirl]

Thanks, everyone!!! This is getting more and more interesting, so many different approaches!

[Witfull]

dry martini....wet foam.

[Travis]

I did some research on this a while back, and the "experts" at that time were arguing that the wet skimmate would strip your water of more good stuff. It was a pretty lively deabte at that time, but I landed in the corner of dry skimmate. Perhaps I should rethink that.

This being the new frontiers forum, I'll try to dig up some old arguments on the subject so maybe we can toss around the ideas presented.

(Times they are a-changing by Bob Dylan running through my mind. )

T

[Travis]

Funny, I remember more than this but here's a start...


http://www.reefs.org/library/article/wet_dry_foam.html

QUOTE: "With wet foam you are removing MUCH FEWER organics and a lot more plain old tank water, so in essence the skimmer is not really working"

This point is argued in the link, not saying it's true...

[Boomer]

Scott skimmers can take a bit of your sodium out of the water. So yes you are corect your salinity will take a bit of a hit.

Hi Mikey

Hmm, Sodium or Sodium Chloride, what about all the other things in seawater, they just don't make it i.e. Sulfate, Mg, K etc.. Some one stick their conductivity meter in the collection cup

Yes, wet foam, not to wet. Dry foam is not a good idea, as the bubble/foam becomes to stable and does not collapse for easy removal. If the foam is to wet, some of the surfactants will just go back into the water. Bubble rate should barely exceed foam collpase. Foam stability depends largely on surfactant concentration. Bubble staility decreases with decreasing surfactants.

A good read

http://home.mweb.co.za/jv/jv79/reef/skimmers2.html

[RanRoc]

very good article, Boomer!
-RY

[mojoreef]

Ok OK iI should have sai that but I was trying to just related it to salinity drop, lol..busted again
That is a great article Boomer I didnt know had done a write up on skimmers.

Travis bo those names in that artical sure bring back some memories

Good thread folks

Mike

[Boomer]

[mojoreef]

Oh Randy?????? Boomer sent us all over here to get some one on one direction on ORP......lol....and how it relates to the use of aqua-ecolizers...rofl...careful I got dirt on ya.

Mike

[Flatlander]

Ok, we need Jerel and his wet foam beckett here.

I can say, my experience with different skimmers, run at different levels, would lead me to think the wet foamers are correct.

My becketts, when running wet, {and like mentioned, not to wet}, kept the tank in great shape.

Two things happened if ran drier. More algae growth, esp. the glass and a much dirtier low riser. {pita}.

And, although I am a big Euroreef fan, my particular model produces to much dry foam for my particular situation and I now have algae growth gain.

[Scooterman]

My AquaMedic 1000 never did make a real dry foam, somewhat wet, I usually supply water very slow producing a thick liquid that smells aweful, I hate cleaning it!

[tankgirl]

Great replies!!! When I did a search on wet foam-dry foam every single article or discussion I found said dry foam was the correct way to run a skimmer.

Basically, the reasons given, for dry foam were;
If the foam contains a lot of protein, however, the upper bubbles reform into a "dry" foam that contains less water and more organics. This dry protein foam "floats" on the wet water foam, accumulates organics from the watery foam beneath it, and is pushed up into the collection cup of a protein skimmer. An optimally adjusted and maintained protein skimmer collects only the dry protein foam and a small amount of the wet water foam. Mostly, this info seems to stem from a study done by Wilkens (TRA 1973)

Did see a couple of statements that mentioned temporarily running a wetter skim production after cleaning the algae off the glass to remove the algae.

However, I've run across several discussions in which Jerel insists wet foam is better, hence the thread.

[Witfull]

1973? that was a long time ago. i am sure methods and technology have changed and further research has been done since.

[tankgirl]

Hi Wit,
I was just hoping to avoid a lengthy post. I guess the initial studies were done back then, but many refs were in the last year or two, and some of them are by people like Deltec (or other skimmer makers)?
Notice Steve Tyree dissents!
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Here's the longer version;
http://www.ctu.edu.vn/colleges/aquac...ailnew/n32.htm
This unedited article first appeared in theMay/June 1991 issue of Aquarium Fish Magazine To Skim or Not to Skim: That is the Question by Scott Dyer and J. Charles Delbeek M.Sc.

An important factor affecting the efficiency of your protein skimmer is foam or "scum" formation as it is often called. Wilkens (1973) discusses two basic types of foam that develop in effective skimmers. The first is referred to as "standard" scum and the second as "protein" scum. It is the second layer, the protein scum that removes harmful organic substances from solution. If your skimmer only produces the standard scum it is not being used effectively.

Standard Scum: The standard scum is the layer of foam that develops as a result of protein molecules uniting with fine air bubbles. Most skimmers will easily extract this layer of foam. However, the amount of harmful organic substances removed in this way is minimal and may not curtail the development of "toxic tank syndrome" etc.

Protein Scum: Protein scum is formed by organic substances, metals, etc. attaching themselves to the protein molecules in the standard scum. Protein scum is therefore found as a second layer beneath the standard scum in the column of the skimmer. In light of this one can see that it is essential that your contact tube be long enough to facilitate the development of both types of scum. Wilkens (1973) states: "In a well adjusted skimmer, the protein scum will slowly rise in the column until it is collected in the foam- cup". He also states: "One will get a proper adsorption and with that a concentration of the proteins on the edge between standard scum and protein scum".
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http://www.marinedepot.com/a_ps_euroreef.asp
Want wet foam because you just cleaned the algae off the glass? Raise the pipe up a bit.. Adding new water, food, live rock, resins etc., which often make a protein skimmer go nuts!!?? Just lower the pipe a bit....
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http://www.animalnetwork.com/fish2/a...ct/default.asp
My preliminary work suggests that the volume of foam generated by a protein skimmer may not be a useful indicator of skimmer effectiveness. Furthermore, while hobby conventional wisdom says dry foam is better than wet foam, it appears that dry foam is richer in particulate matter than wet foam.
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Harker, R. 1998. The case for the counter-current skimmer. Marine Fish and Reef USA 1:56-66.

Lush, J. 1976. Orifice spirator as a foam fractionation air injection system: design effects. Masters thesis, University of Maryland, College Park, MD.

Schiemer, G. 1995. Beyond the instructions - Introducing the ETS skimmer. Aquarium Frontiers Winter:21-23.
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http://www.algone.com/protein_skimmer.htm
An interesting aspect is that skimming will reduce pheromones. This hormone is released by the fish as a form of chemical communication. Pheromones influence the fishes’ behavior such as reproduction, migration, schooling, feeding, predator-prey and other interactions.

Pheromones in higher concentrations will suppress the immune system of the fish making them more vulnerable towards disease and parasites. As it is the same with high DOC levels, a protein skimmer will lower them to healthier levels.

Too much air injected will cause excess foam which will remove more water then DOC’s. This is referred to as “wet foam”. “Dry foam” on the other hand is the result of too little air or water flow.

The foam of the skimmer should be beige (ginger ale like) in color; this indicates that the skimmer is working well. Producing dark foam means that the protein skimmer has to be adjusted (adjustments can take days to show results).
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http://www.simplifiedreefkeeping.com/faq/skimmers.htm
My ETS Skimmer is foaming, but I'm not sure how to adjust it. So far the foam has reached the collection cup but has never overflowed. That will take some time, probably a week or so before it starts to "kick in" and produce nice dry foam. A common mistake is to set the skimmer too high and that produces a wet foam. You probably wont get much actual skimmate (real thick gunk for about a month) It takes allot of dry foam and a kicked in skimmer to get that. Patience...
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http://bobbates.net/html/protein_skimmer_theory.html
The stabilized bubbles form a temporary foam above the water surface. This foam, termed the foamate, contains water soluble proteins, amino acids, some organic dyes, fatty acids, fats, carbohydrates, enzymes, detergents, many inorganic compounds, metal ions (particularly copper and zinc) that are tied up in sulphide compounds, iodine, phosphorus, tiny cells of algae, protozoa, and bacteria, and tiny buoyant particles of organic detritus.

When the foam is first formed, the water content is high and it is quite "wet". As the foam breaks down, the water drains downward carrying dissolved and particulate matter. If the foam contains a lot of protein, however, the upper bubbles reform into a "dry" foam that contains less water and more organics. This dry protein foam "floats" on the wet water foam, accumulates organics from the watery foam beneath it, and is pushed up into the collection cup of a protein skimmer. An optimally adjusted and maintained protein skimmer collects only the dry protein foam and a small amount of the wet water foam. If there is little protein or other organic colloids present in the water, dry foam does not form, and the optimally adjusted protein skimmer collects little material. A protein skimmer operated at this adjustment point collects most of the excess protein and organics, but since foam collection does not include much of the constant production of wet foam, loss of trace elements is minimal.

A skimmer that continuously produces a lot of wet foam is also likely to reduce the trace elements required for strong algal growth.
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http://216.239.39.104/search?q=cache...hl=en&ie=UTF-8
At its lowest setting, the skimmer may collect an extremely wet, light-colored froth at first. In order to collect a dry foam, raise the collection cup a small amount each day until you find the desired level.
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http://www.thereefweb.com/protein_sk...comparison.htm
Often, a lot of attention is paid to the consistency of foam -- dry foam being considered preferable.
It is important to understand that the only difference between dry and wet foams is the amount of water, not the amount of dissolved organics.... in skimmers, wet foam still removes just as much dissolved organic matter; it just removes more water with it. If you remove so much water that you overflow your collection cup, the wet foam becomes counter-productive, but until that point, it is just as productive as dry foam.
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http://www.netpets.com/fish/reference/srab/srab5c.html
For every "load" there is an ideal flowrate, and that flowrate cannot be determined unless you have a redox controller. Since this is not a unit that we will include in a basic set up, we need to look for other ways of approximating that gph,A and end up with an efficient skimmer. To do this, we need a few more explanations about protein skimmers...
Wet foam, mostly plain water, is not properly skimmed water, and contains much less of the organic and other elements we wish to remove, than a dry foam, that is heavily concentrated, dark in color, and thick.
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http://www.thekrib.com/Marine/plankton.html
In article
I have an ozone test kit and have never measured any residual ozone in the tank. The skimmer produces very dark liquid via wet
foam. Steve Tyree
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http://www.wetwebmedia.com/bestskmopfaqs.htm
Food supplements, such as Selcon (vitamin C), added directly to the water retards foam production
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http://www.fishkeepersforum.org/hard...mmer%20FAQ.asp
The better skimmer produces less, but more concentrated gunk. This may be hard to detect by eye, since many proteins are clear (like egg whites).
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http://www.reefs.org/library/talklog...do_071998.html
How does a skimmer remove phosphates?

A skimmer removes phosphates mainly by floatation. It exports it out of the system in the skimmate. It works better with larger producing skimmers

Does it matter whether your skimmers produces wet or dry foam?

Dry foam is better, in my opinion. Wet foam is not as concentrated but I have heard from others that they use it to sort of perform continuos water changes on their system and so prefer to have a small amount of wet foam constantly.
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http://216.239.39.104/search?q=cache...hl=en&ie=UTF-8
Close down the tap slightly if an initial very wet skimmate is being produced this is normally produced by removal of a conditioning compound that is found in some salts.

[HAP]

My Turbo Flotor 1000 Multi produces a bit of a wet foam. It'll fill the collection cup with nasty green water full of particles every 2-3 days (sooner if I stir the tank). So I guess I am going with wet foam since I can't argue what appears to be working for me.

It may be a factor not only of personal preference but also a byproduct of the type of system you have, the livestock you keep, the type of skimmer you are using and many other variables. No two reefs (from what I have seen since getting into this) are alike.

But thats just me thinking out loud again...