Fact or Fiction - Skimmers

[E-A-G-L-E-S]

In the quest to find the ideal skimmer for my set-up. I've come across many statements, beliefs, facts, etc.
I wanted to post these in an effort to find the truth in the middle.
Thank you for any help in advance!

1. The smaller the bubbles the better
2. A skimmer should process 1 to 1.5 your tank volume per hour
3. A skimmer should process as much water as possible, the more the better
4. Skimmer body size
A. Bigger the better
B. You must match size to system size
5. You cannot overskim
6. Your skimmer can be too large for your system and be a waste of money and perform less than it's smaller brother
7. External skimmers are better than in-sump
8. The more air you pull the better
9. you must match your air intake to your gph for an ideal skimmer
10. Gravity feeding a skimmer is always the best option if it can be done
11. Recirculating skimmers are a must
12. Recirculating skimmers are a waste and woud be bettered by their larger non-recirc. brother
13. It's all about the pump
14. It's all about the skimmer design
15. Funnel/cone necks are better than flat

 

[USC-fan]

what type of skimmer are you talking about?

each type will give you different answers.

 

[Inflames]

I predict this thread splitting at least twice

 

[E-A-G-L-E-S]

None in particular, just the thought processes behind their operation. Many reefers believe one skimming 'way/process' is 'the' way and the things I listed above are the varied reasons behind their answers.
So if each skimmer is unique what about them makes them that way and what do they do that makes their way best?

 

[Andrew]

1. The small the bubbles, the better is true. If you have smaller bubbles than you are more likely to pick up small particles floating around.

2. True in some cases. It also depends on what type of tank is it and what your bio-load is.

3. Same as above

4. The skimmer body size needed will again depend on the type of tank and the bio-load in the tank.

5. True. I have not seen any problems with over skimming but if you slap a Deltec 702 on a 20 gallon tank, the skimmer will be too powerful and you will notice you won't get much skimmate.

6. True. Same as the example in #5

7. True in some cases. It really depends on the pump and the amount of air being pulled in.

8. True. The more air that is pulled into the skimmer before the pump the better. This will create more bubbles and depending on the impeller, finer bubbles.

9. ?

10. Not always true but will save energy.

11. Pretty much an opinion. The skimmer needed will depend on the tank.

12. Again, another opinion. An external bubble king won't preform worse than an in the sump one. Depends on the skimmer, pump, and air intake.

13. I wouldn't say it's all about the pump, but the impeller and venturi also play a major role.

14. Can be true but I've seen many types of skimmer preform the same. Even airstone driven skimmer will work just as good as some of those nice fancy skimmers out there.

15. I would have to say True but can also depend on the skimmer layout and design. A flat neck will give bubbles time to group and join together. If you have a cone than the bubbles will have less time to join. The skimmer the bubbles the better the foam production.

 

[E-A-G-L-E-S]

So....
smaller the bubbles the better - always
the more air the better - always


....how do you match the skimmer size, pump gph, air intake pull to your set-up?

And how do you determine which 'style' is right for your set-up?

 

[E-A-G-L-E-S]

What about dwell time as well? Which method allows for longest and is the longest ideal?

 

[jeffbrig]

1. The smaller the bubbles the better
True. Smaller bubbles maximizes surface area, which is where you collect proteins.

2. A skimmer should process 1 to 1.5 your tank volume per hour
A decent rule of thumb, although it's more important to consider the skimmer body volume vs. flow rate, and what that means as far as dwell time (the time a given bit of water spends in the skimmer). I've heard 2 minutes tossed around as a good target, and my skimmer happens to be pretty close to that at 1-1.5x.

3. A skimmer should process as much water as possible, the more the better
Within reason, but again, consider dwell time. Move too much water through too quickly, and you may not be as effective.

4. Skimmer body size
A. Bigger the better
B. You must match size to system size
A bigger body is capable of handling a larger system or larger bioload, provided the air injection and water flow rates match. But, there is only so much material to skim. Once you have a size that meets the tank's needs, anything bigger is unnecessary. I recommend buying the biggest you can fit/afford, you can always use it on a bigger tank when you upgrade.

5. You cannot overskim
Subjective, based on what you mean by "over". Can a large skimmer take nutrients out of the water - yes. Can that be detrimental - perhaps (I've never experienced it). Is this a problem for most systems - no.

6. Your skimmer can be too large for your system and be a waste of money and perform less than it's smaller brother
It won't perform less, it will perform the same. The nutrients in the tank are the same. The large skimmer may perform below it's potential if oversized relative to the tank, but it won't perform worse than the smaller one. Whether it's a waste of money is subjective - a bigger skimmer may give you some margin of safety if, for example, a cucumber jumps into a powerhead and tries to nuke your tank. What's that worth to you?

7. External skimmers are better than in-sump
Doesn't matter from a performance perspective. After that, there's arguments both ways. External means less heat added to the sump. In sump dumps back into the system if it overflows (this could be good or bad depending on circumstances). FWIW, I run my external skimmer in-sump, simply because that's where I had room for it.

8. The more air you pull the better
Yes, but only to the point that you can still make tiny bubbles. At some point, lower airflow with smaller bubbles will beat higher flow with larger bubbles.

9. you must match your air intake to your gph for an ideal skimmer
I'm not sure if this is something you need to worry about, especially with recirculating designs where air injection is independent from flow.

10. Gravity feeding a skimmer is always the best option if it can be done
I believe it's beneficial to do it if you can. At worse, it eliminates a feed pump, needless power consumption and heat. At best, it may skim a little better by making sure surface proteins go through the skimmer, which may or may not happen as much with an in sump pickup.

11. Recirculating skimmers are a must
Not a must, but a good design. For a given pump, changing it to recirculating uses less power, and injects more air. If it can produce small bubbles, it will work better.

12. Recirculating skimmers are a waste and woud be bettered by their larger non-recirc. brother
For the same body and pumps, recirc will outperform. If you're comparing to a different larger body, you're comparing apples and oranges.

13. It's all about the pump
Depends on what kind of pump we're talking about. For a needlewheel, the pump/impeller combo is a big factor in overall performance. For a downdraft or beckett, I don't know that it matters as much.

14. It's all about the skimmer design
You decide. I don't know you're referring to skimmer type, body size, pump selection, impeller, etc.

15. Funnel/cone necks are better than flat
I would be surprised if the difference was signficant.

 

[E-A-G-L-E-S]

Some great stuff, thanks!

So dwell time is more important than mass process?

So how do you know the 'right' amount of flow for ideal dwell time?

How do you match a skimmer to your set-up and bioload and feeding habits? What style/method of skimmer is best for your set-up?

 

[E-A-G-L-E-S]

bump....

 

[jeffbrig]

So dwell time is more important than mass process?
No, they're both important, and a larger body lets you have both. Now, don't you wish 12" acrylic was cheaper than it is?

So how do you know the 'right' amount of flow for ideal dwell time?
Calculate the volume of the skimmer body (pi*r^2*h for the main cylinder). To achieve 2 minute dwell time, you want to turn over the skimmer volume 30 times an hour. My skimmer works out to 10g internal volume. 30x an hour would require about 300gph feed rate.

(Note that the 1-1.5x tank volume turnover recommendation happens to fit very nicely here)

How do you match a skimmer to your set-up and bioload and feeding habits?
The more stuff you want to keep, the bigger the skimmer you will need. Rather than reading mfr recommendations (some are just laughable, especially on the cheaper end) look at what successful tanks are running, and what they have as far as bioload to gauge what size of skimmer you should have. I think mine is rated for a tank more than twice the size of my actual system.

What style/method of skimmer is best for your set-up?
Up to you, any of them can be successful. Most people are huge advocates of what they use and are familiar with. Personally, I like needlewheels (but I'm not going to tell you they're the only way to go). They can be short and wide, which may help if you want to keep the skimmer inside a stand. They're pretty quiet, low in power consumption, and are set-and-forget. Beckett skimmers tend to require larger pressure-rated pumps (more electricity, noise) and may require more tweaking. An old fashioned airstone driven downdraft skimmer can also work, but may need to be very tall to be effective.

 

[bernie lyons]

skimmer

skimmer

I disagree with some of the points because it necessarely doesn't always prove to be the case all the time :
- smaller bubbles do remove proteins better but in a case in which i used a beckett design , I experimented with the air valve partly closed to get a small bubble size but hair algea was
growing like crazy. Then I decided to open the air valve all the way and the hair algea disappeared after two weeks and never came back again . So i believe that a mixed bubble size does have it's advantages , it seems to lift the algea spores out better partly due I believe to the turbulence created at the neck and thrusting the spores on to the foam .
Recirculating skimmers obviously have better dwell time , but in the case of becketts , co-current processes the water more often in terms of protein skimming and degases your aquarium more often.
I've compared a needle wheel design (deltec ) skimmer vs a single beckett , both measured at (850 litres an hour) and
and there is no question that each skims differently .
The beckett design is more efficient over all in terms of skimming but uses more electricity .
cheers
bernie lyons

 

[E-A-G-L-E-S]

jeffbrig....your skimmer holds 10g of water? It must be gigantic!

 

[jeffbrig]

Euro-Reef RC500, 12" diameter, 30" tall. I only count it as 20" tall for the volume calculation, since the rest is foam in the neck and the collection cup.

 

[gasman059]

I like this thread.

I like this thread.

For a downdraft or beckett, I don't know that it matters as much.

On the contrary IMO its all about the pump and the pressure rating of it. As u know Jeff i'm a big fan of downdrafts and in my experience they work better with pressure rated pumps.

Personally, I like needlewheels (but I'm not going to tell you they're the only way to go). They can be short and wide, which may help if you want to keep the skimmer inside a stand. They're pretty quiet, low in power consumption, and are set-and-forget. Beckett skimmers tend to require larger pressure-rated pumps (more electricity, noise) and may require more tweaking. An old fashioned airstone driven downdraft skimmer can also work, but may need to be very tall to be effective.

As far as set and forget I disagree, needelwheels require tons of tinkering with IME.
As far as set and forget becketts and downdrafts are by far the best. If i was setting a 5-700 gallon system which BTW i'm considering there's no doubt in my mind i would choose a beckett or downdraft leaning a little towards downdraft.

As far as the rest Mr. Jeffbrig hit the rest on the nose IMO.
BTW I feel like I'm going be underskimmig my tank sooner than later LOL.
THIS IS WHAT I LIKE DOWNDRAFT IMO AETECH ETSS
I DONT CARE ABOUT EXTRA BILL AND DEF DONT CARE ABOUT PRETTY .

[/IMG]

 

[jeffbrig]

Re: I like this thread.

Re: I like this thread.

As u know Jeff i'm a big fan of downdrafts and in my experience they work better with pressure rated pumps.

As far as set and forget I disagree, needelwheels require tons of tinkering with IME.

And on the other hand, I haven't touched an adjustment valve on mine in months.

But like I said before, we each tend to recommend what we use and prefer. The key point is that any style of skimmer, if properly sized for the tank, can be effective.

 

[gasman059]

And on the other hand, I haven't touched an adjustment valve on mine in months.

LMAO i knew that was coming LMAO anyways -seriously I've had needelwheels(euro) modded and it was great worked very well but INO not well enuff.

 

[nyvp]

so jeff how do you figure my skimmer in to this equation :rollface:

 

[E-A-G-L-E-S]

nyvp....Could you explain the type of NW Spazz built you?

 

[King-Kong]

Eagles,

Many BB users experience over-skimming (SPS corals faded, pastel colors). The solution is: feed more, get more fish! (nice excuse!)