Skimmer or Refugium

[Lasse]

This also explains why things like Melafix (containing oils in a water-soluble form) and soap are removed by protein skimmers.

They are not removed in a concentrated form in the foam -they cause the foam to collapses (the concentration mechanism) and many times make the skimmer overflow and the concentration in this overflow out in the skimmer cup is the same as in the water column. It is a type of WC.

Freshwater skimming will not concentrate unwanted compounds very well but for brackish water it works sometimes even for some nonpolar compounds. Skimming in saltwater above 25-30 PSU only works for amphiphilic substances (read mainly proteins) - but on the other hand it works very well.

protein skimmer to produce more foam are not necessarily removed by them

The foam consist of concentrated substances - proteins in water above 25 - 30 PSU are one example. But those substances you mentioned does not produce more foam (IME) in this type of saltwater - they make the foam to collapse - which means concentrations not much above the concentration in the water column.

Sincerely Lasse

 

[Privateye]

They are not removed in a concentrated form in the foam -they cause the foam to collapses (the concentration mechanism) and many times make the skimmer overflow and the concentration in this overflow out in the skimmer cup is the same as in the water column. It is a type of WC.

Freshwater skimming will not concentrate unwanted compounds very well but for brackish water it works sometimes even for some nonpolar compounds. Skimming in saltwater above 25-30 PSU only works for amphiphilic substances (read mainly proteins) - but on the other hand it works very well.


The foam consist of concentrated substances - proteins in water above 25 - 30 PSU are one example. But those substances you mentioned does not produce more foam (IME) in this type of saltwater - they make the foam to collapse - which means concentrations not much above the concentration in the water column.

Sincerely Lasse

I'm still not understanding something. If amphiphilic molecules are removed by protein skimmers (in a concentrated form) then why wouldn't soap be removed? It's amphiphilic. Or in the case of Melafix, an emulsified oil.

Part of this line of questioning is I'm wondering whether a protein skimmer "accelerant" would be a viable product for our industry.

 

[Lasse]

in a concentrated form in the foam

If amphiphilic molecules are removed by protein skimmers (in a concentrated form) then why wouldn't soap be removed? It's amphiphilic

As I try to explain earlier:

The high ion concentration together with the tiny bubbles in a skimmer force those amphiphilic substances to the air/water surface of the bubbles. (thermodynamic driving force / "salting-out") Upon reaching this interface , they undergo surface denaturation, whereby the hydrophobic end attaches to the gas phase at the interface and the hydrophilic end attaches to the water. What happens next is that the amphiphilic substances form a rigid, viscoelastic network (intermolecular cross-linking/gel formation) that stabilizes the foam which builds up and is transferred into the skimmer cup. This is mainly proteins but some other larger amphiphilic substances may also be a part of this network.

On the other hand - detergent molecules are significantly smaller and diffuse more readily, they move faster toward the air-water interface, thereby physically displacing the larger amphiphilic substances (competitive adsorption).

Within the water column itself, detergent monomers encapsulate the larger amphiphilic substances. This masks the non-polar regions of these substances, neutralizes the "salting-out effect," and eliminates the thermodynamic driving force that causes the amphiphilic substances to migrate toward the air bubbles (macromolecular solubilization).

The result will be less stable foam - lesser concentrations of "unwanted" substances. If the skimmer will "overrun" because of this type of substances - the concentrations of all substances is the same in the "overrun" as in the water column

If we talk about soap only - its true that it is amphiphilic but in a water rich in Ca and Mg - mostly Ca bounds to the soap molecule - and form sticky precipitate on all surfaces. Instead of forming a clean micelle this chemical reaction creates an insoluble, sticky precipitate commonly known as soap scum. (micelle is the tiny sphere formed by the amphiphilic soap , keeping the oil or fatty particles trapped on the inside and the water-loving heads exposed on the outside),

This sticky sticky precipitate - calcium soap ((RCOO)₂Ca) is completely insoluble in water - stick on surfaces - As far as I know, this precipitate will not incorporate other substances—only calcium and magnesium.

This reaction have nothing with a skimmer to do - it happen directly when the soap molecule enters the saltwater.

Sincerely Lasse