Skimmer Ratings- a discussion.

[Powerman]

Right, I'm not trying to get a hard figure from that, just an idea of whats going on.

 

[gcarroll]

Great discussion everyone. I have found that everyone has different opinions as to skimmer rating but I will tell you that there are either exceptions to every rule or there are no rules!

I lean toward the opinion that there are no rules.

You are always going to find people that are successful even though they are using a skimmer that is either too large or too small according to the skimmer experts.

I like and use a cone however, of the best tanks that I have ever seen in person, none were running a cone. Only one ran a skimmer that would even be recommended by today's skimmer experts.

Here are the specs of some of the best tanks that I have seen.
500g (display)/1500g system = ETSS 2500
225g (display)/400g system = ETSS 2500
800g (display)/1000g system = 2x ASM G5
100g (display)/120g system = BK Supermarin 250
300g (display)/400g system = MRC-4 beckett

Of all of these tanks, the tank running the ASM's is currently the best tank I have ever seen!

As some of you may remember, I used to run AquaC but that changed as electricity rates in California skyrocketed and the $300-500/month e-bills started rolling in. I still beleive that my AquaC did a fine job and I could argue that it was as good as any of todays skimmers but I won't go there.

 

[Jeremy R.]

Nice to see you here Greg. Although AquaC skimmers gets a mediocre rep, I agree with you and loved both AquaC skimmers I have owned. The trick is understanding how they work which I think is what usually leads to frustration among many users. If energy costs, sound and time to fiddle around with skimmers wasn't an obsticle I actually like Becketts and Down Drafts on large systems and spray injections on smaller ones. But the majority of today's Reef keepers are also looking for an efficient easy to use set and forget skimmers.

 

[Powerman]

Personally I have never had a problem with how well AquaCs or Becketts actually make bubbles..... as far as the efficiency, set and forget part.... ya, why spend more money and time to do the same job?

Which is another interesting part of skimmer ratings.... cause while most are concerned with turbulence and contact time and air draw, Beckets still skim well and are quite the opposite of todays needle wheels. Which was another reason for this thread of how can a Beckett be so good at skimming yet be so contrary to todays trends and numbers?

One obvious part of some sort of rating criteria woul dbe how well a design performs. So if a cone is "better" it should be rated for a little bigger tank given equal numbers with a cylinder. By that reasoning Becketts should be downgraded accordingly because of how they do it.... yet Becketts have their place and are not "limited".

 

[ksed]

Point very well made!
I hope someone has an answer for that!

 

[Jeremy R.]

Becketts need large pressure rated pumps to feed the beckett injectors and process a ton of water per hour compared to any of todays pinwheel/needlewheel skimmers. In fact most if not all Becketts and downdraft skimmers are powered by pumps that are more and sometime 2-3X the flow of there return pump. That is a lot of water processed and for as much water that is pushed through the injector air is also pulled. There is also ton of dwell time and if you ever see the neck/stacks on one you will see how steady and dry the foam head formation is. This is why the necks need more than normal maintenance cleaning and constant adjustments by the owner because they build up with crud. In fact majority of the larger powerhouse pinwheel skimmer today remind me or the steady and dry head of foam collum like the beckett are known for producing. IMO Becketts will always have there place in the hobby for those that want the large, noisy and tinker prone powerhouses for their large systems.

 

[Crazy Rick's]

Excellent thread!

Steve

 

[ksed]

Which is another interesting part of skimmer ratings.... cause while most are concerned with turbulence and contact time and air draw, Beckets still skim well and are quite the opposite of todays needle wheels. Which was another reason for this thread of how can a Beckett be so good at skimming yet be so contrary to todays trends and numbers?

nobody!

 

[Jon Warner]

As I've said before... skimming is an equation. A little more of this is equal to a little more of that. Most Beckett skimmers have MASSIVE reaction area volume and great water turnover. They drive ORP up and work well WHEN they're spot on.
Protein Skimming on any level is a compromise. In a perfect world, skimmers would ALL be 6' tall, lol...

 

[Powerman]

What is considered reaction chamber? Most AquaCs and Becketts have tiny boxes, but huge long necks. I always considered reaction chamber as the bubble water mix.... once it turned to foam, I figured that was it. So that's cool if Becketts ahve a lot of contact time and turn over.

Actually Jon... we have talked about variables... but putting it in terms of an equation helped out a lot.

 

[ksed]

Thanks Jon!

 

[hawaiireef]

imho, there are 2 relevant skimmer equations, one for efficiency, one for throughput. skimmers for larger and smaller systems would be an issue of the speed of removal of waste (throughput). However, ultimately the quality of the water coming out of a skimmer is a matter of efficiency. This is probably consistent with the idea of "balance" between type of skimmer and tank size.

efficiency = (contact time X bubble size X foam stability) divided by neck size (narrower neck pushes foam out faster and is more efficient)

efficiency X throughput (gallons/hour) = ability of a skimmer to serve a tank of a particular size.

best for large tank would probably be 2 skimmers plumbed in-line: less efficient skimmer first (wider neck to avoid flooding) feeding directly into a more efficient skimmer to drive a higher % of waste removal.

 

[Powerman]

best for large tank would probably be 2 skimmers plumbed in-line: less efficient skimmer first (wider neck to avoid flooding) feeding directly into a more efficient skimmer to drive a higher % of waste removal.

And what do you base this on? There are those that choose to run multiple skimmers on large tanks, but I have yet to see any one run staged skimmers. I'm sure it has probably be tried at some point, I've just have not seen it. Of course I don't know much about very large systems, but I have seen very large skimmers and they were just single stage.

What units are foam stability expressed in?:bigsmile:

 

[Troylee]

I personally would rather run one large than 2 smaller... The second skimmer would only perform so well because something else is already doing it's job...running the drain into the body of another skimmer would be like running it recirc on a single... Not nessacary IMO....

 

[hawaiireef]

let me step back and say that this is hypothetical, although I will probably be building a 2 stage skimmer at some point. Foam stability would be a measure of turbulence at the surface of the water, could be expressed as a ratio of vertical versus horizontal bubble movement.

On third thought, the overriding equation should be related to water quality:

water quality = throughput X efficiency

 

[mojo]

I started thinking more and more about what you are saying. And again it is kind of a inefficient recirc skimmer. Maybe you could prove me wrong here. but what I envision is just that.

Mojo~

 

[Troylee]

I started thinking more and more about what you are saying. And again it is kind of a inefficient recirc skimmer. Maybe you could prove me wrong here. but what I envision is just that.

Mojo~

my thoughts exactly.....
please post if you do come up with something..it's a interesting concept but i cant figure a way that would be effciant or better than one propper size skimmer....
what size tank are you thinking about doing this on?

 

[Powerman]

let me step back and say that this is hypothetical, although I will probably be building a 2 stage skimmer at some point. Foam stability would be a measure of turbulence at the surface of the water, could be expressed as a ratio of vertical versus horizontal bubble movement.

On third thought, the overriding equation should be related to water quality:

water quality = throughput X efficiency

Originally, the point of Jon exspressing his opinion on equations made it simple as a representation of a idea. That with all the variables, a balanced equation would mean that if you increased one variable, then others could be decreased. That in a balanced skimmer, all the variables at various values end up as an overall skimmer rating.

However, an actuall mathmatical equation on skimmer efficiency or capacity is.... well....uh.... you are really over reaching here.

Water quality is a simple measure of various contaminates. You define what a contaminate is. The rate at which you can clean any such contaminate will be determined by flow (for time) and efficiency. But water quality does not = flow X efficiency.

Foam stability has nothing to do with surface condition at the interface if what you have above that is a horrible transition to the neck or not enough air to get it to the neck. I mean I get expressing ideas, but there is no such measure or units for foam stability other than anectodal observation.

 

[hawaiireef]

This would be on 100 gallon

Regarding whether or not a skimmer and tank water quality can be reduced to equation(s), I would think that clearly our ecosystems are governed by observable processes that can be represented mathematically. A certain skimmer of specific parameters (whatever you think that the relevant parameters are ) should be able to reduce organics by whatever percentage in a given amount water in a given amount of time. This would be the only empirical, objective way to rate skimmer efficiency. Now this rating can be derived two ways - either through experimentation (dump a bunch of junk in the tank and figure out how much the skimmer removes) or by theory, which it seems to me what this thread is.

Now, whether or not we are smart enough (and I mean myself included) to figure out those variables, thats on us, not an inability for what happens in a skimmer to be described mathematically.

Here's where I get hung up on this conversation so far. The idea that a certain size skimmer works better on a certain size tank. In reality, the skimmer has no idea what size tank it is hooked up to. Its output is only driven by the amount of dissolved organics in the water. So take your biggest skimmer, hook it up to a 10 gallon tank, and drop a dead carp into the tank and it will "skim" like crazy.

The "balance" that we are talking about comes into play when you consider that if you hook a superefficient skimmer up to a very large tank, but dont have enough throughput, the water coming out of the skimmer will be super clean, but since it doesnt turn over the tank fast enough, DOCs in the tank water that have not yet been processed are converted to nitrates before they have a chance to hit the skimmer.

On the other hand, push a ton of throughput through an inefficient skimmer, and the wtaer doesnt come out clean.

Is there a way to combine the throughput with efficiency in an elegant (for instance, energy efficient, small footprint) way, without resorting to simply overpowerign the skimmer (i.e, the "6 footer", which I've owned, btw).

 

[Troylee]

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!!!!!!!