Why do oversized protein skimmers not adequately remove protein from a tank?

[Salt water taffy]

I don't understand why oversized skimmers do not adequately remove dissolved protein/waste from aquariums. Using arbitrary units, let's say that when maintaining a tank, one wants to have a protein level that is below 20. Let's say that we have a 500 gallon tank, that has lots of life in it, and lots of food is being fed. Let's say prior to turning a large skimmer on, the protein level in the tank is at 30. After turning a large skimmer on, one week later, the protein level goes down to 18.



Now let's say that we have a 75 gallon tank that has lots of life in it, and lots of food is being fed. Let's say prior to turning the same large skimmer (the same that was used in the 500 gallon tank) on, the protein in the tank is at 30, and we again let the skimmer run for one week.



In the second scenario, 75 gallons, the total amount of life in the tank, and food being fed, will be assumed to be far less than was the case with the 500 gallon tank. This is because a heavily-stocked 500 gallon tank simply can't hold as much life as a heavily-stocked 75 gallon tank. However, in this case, since the 75 gallon tank is 15% the size of the 500 gallon tank, not nearly as much life and food is needed to bring the level of protein in the tank up to 30.



It is my understanding, that in the second scenario, with a 75 gallon tank as opposed to a 500 gallon tank, the oversized skimmer will not bring the level of protein down to 18, as it did in the first example. The reason for this, is that for some reason, it is stated that oversized skimmers do not do a good job of removing protein.



One explanation that I've heard for this, is that the diameter of the bubble collection chamber in a skimmer must be smaller for a tank of low volume, and larger for a tank of high volume . So, using a large diameter bubble collection chamber in a small aquarium won't allow sufficient frothing of protein-rich water, thereby making the collection of this protein-rich foam inefficient.



Assuming my above understanding is correct, and it might not be, this doesn't make any sense to me. If water going through a skimmer has a certain concentration of protein in it, why does it matter what the total volume of the tank is? If you have water in a skimmer, that has a protein value of 30, why does it matter whether there is a lot of extra water, or a little bit? In each case, the parameters of the water immediately in the skimmer should be the same, right?



What am I not understanding about this situation?



Thanks

 

[wvned]

I dont think you assumption is always correct. I have 2 large skimmers. The Reef Octo SRO 8000 is a typical needle wheel cone type shimmer. The neck diameter and how far the foam must rise are large. I dont think it would raise much of the skim into the cup over time unless you adjusted it to just under blowing out the top.
I also have a 30 inch tall Lifereef venturi skimmer. It has a small neck typical of the size of much smaller cone skimmers. I think it would skim your hypothetical small system fine.

Both these skimmers have large pumps that would turn over you sump volume many times faster than a small one would as well.
I am sure some of the collected stuff must escape from the skimmer. If that happens before it can form enough foam to get it to the cup it would explain you hypothesis.

Most of what my skimmers do it polish the water. What they collect looks like dirty mop bucket water. 4 gallons at a time.

 

[kharmaguru]

I think the only factor is stability of the foam head. A giant skimmer has a proportionally giant neck and therefore needs proportionally larger protein quantities to create a stable foam head that can be collected. Mod your giant skimmer with a narrower neck and it will likely outperform the smaller skimmer with the same neck. The risk is the bigger skimmer being a foam cannon at various times and potentially causing a mess.

 

[wvned]

Yes

I think the only factor is stability of the foam head. A giant skimmer has a proportionally giant neck and therefore needs proportionally larger protein quantities to create a stable foam head that can be collected. Mod your giant skimmer with a narrower neck and it will likely outperform the smaller skimmer with the same neck. The risk is the bigger skimmer being a foam cannon at various times and potentially causing a mess.

That happens anyway sometimes.

 

[Salt water taffy]

Both these skimmers have large pumps that would turn over you sump volume many times faster than a small one would as well.

This is interesting, I've never even considered this possibility.

Mod your giant skimmer with a narrower neck and it will likely outperform the smaller skimmer with the same neck.

How could this be done? I have a reef octopus int 150.


Thanks for the replies

 

[wvned]

Lol

And these aren’t large skimmers. Just big tittle skimmers

 

[Salt water taffy]

Lol
View attachment 32412731

View attachment 32412732

And these aren’t large skimmers. Just big tittle skimmers

In light of my post, I didn't want to give the impression that I have a massive skimmer that I'm looking to use for a smaller tank. Primarily, I just wanted to find out the theory behind the issue. I would agree, that the INT 150 is small relative to a truly large skimmer, and was wondering if there was a way to size down the neck. I can't think of a way, and I'm probably just better off getting a smaller skimmer.

 

[wvned]

In light of my post, I didn't want to give the impression that I have a massive skimmer that I'm looking to use for a smaller tank. Primarily, I just wanted to find out the theory behind the issue. I would agree, that the INT 150 is small relative to a truly large skimmer, and was wondering if there was a way to size down the neck. I can't think of a way, and I'm probably just better off getting a smaller skimmer.

Well, your post gave us no sense of what size we were talking about. I used mine on a 75 gallon tank. I just never get rid of anything.
I think you could neck down one with some heat formed PVC pipe. Make it into a cone shape so it fits to the side and insert it in from the bottom.
3 or 4 legs from the length of the pipe that sit on the bottom.

 

[kharmaguru]

This is interesting, I've never even considered this possibility.



How could this be done? I have a reef octopus int 150.


Thanks for the replies

This was my swc Extreme 160 with a swc 120 cone cup on it. I 3d printed an adapter and it worked great.

 

[Salt water taffy]

Well, your post gave us no sense of what size we were talking about. I used mine on a 75 gallon tank. I just never get rid of anything.
I think you could neck down one with some heat formed PVC pipe. Make it into a cone shape so it fits to the side and insert it in from the bottom.
3 or 4 legs from the length of the pipe that sit on the bottom.

That's a really good idea.

I didn't mention the size because the question isn't in reference to a clear and present issue. My tank currently is not set up, it's 90 gallons, and I'm thinking at some point in the future I might want to set up a small tank. I'm just looking for the theory behind all this, Which you guys have provided. Thanks again.

 

[Salt water taffy]

View attachment 32412733

This was my swc Extreme 160 with a swc 120 cone cup on it. I 3d printed an adapter and it worked great.

Cool!

 

[wvned]

I think it would do fine on a 90.
q

 

[Paul B]

I think if you click on the Xs, you can see the pictures. I hope so anyway.

This is because a heavily-stocked 500 gallon tank simply can't hold as much life as a heavily-stocked 75 gallon tank.

I don't understand this but I don't understand a lot of things.

Remember, a skimmer doesn't remove many things, only some on purpose and some accidentally. The on-purpose things are some of the pollutants and a certain molecule that on one side are attracted to water and the other side is repelled by water so they are perfect for a skimmer to remove because they form on the surface tension of a bubble like we have in skimmers. Other things like uneaten food and particles are just stuck to the surface tension and are removed.

This week I rescued this Horseshoe crab. You can see the foam in the water, and that is the Atlantic Ocean where there is no skimmer. If we had a skimmer the size of Alaska, we could remove this stuff from the sea. But it doesn't seem to be bothering anything.



I built my 5' skimmer decades ago and it works well. I inject ozone into it to improve it's efficiency although, not being a chemist, I am not sure if it improves skimmer performance or just by passes the skimmer function and destroys the organics on it's own. I don't really care.



I know my skimmer is removing a lot of "something" and it smells and looks funky so I assume it is better to remove it.

Sometimes I add something to the water that makes the skimmer go nuts, so I figure it is removing those things.

The reason for this, is that for some reason, it is stated that oversized skimmers do not do a good job of removing protein.

A skimmer is not really removing protein, it is removing mostly DOCs which is dissolved organic carbons and although we call them "Protein Skimmers" their real name is "Foam Fractionators". We don't need them, but I feel they are a great help in any tank.

I am not sure how much the neck size effects production because it's all about how much water flows through the thing and the amount and size of the bubbles. Smaller bubbles are better because they have more surface area.