New Skimmer – Price is no Object!

[pjf]

Hahnmeister,

Your design below has all of the features that I want:

• Water inlet at top for greater contact height
• Air introduction at the bottom for greater contact height
• Counter-current flow for greater dwell time
• Recirculation
• Bubble plate for reduced turbulence

Let me know where you plan to have it custom-built. For my 100-gallon system, I’m planning to reduce it to dimensions similar to that of an H&S A150-F2001:

• 6-inch diameter body
• 26-inch height (must clear 28� cabinet ceiling)
• 4-inch diameter bubble plate

Thanks very much!

Originally posted by hahnmeister

[BeanAnimal]

• 6-inch diameter body
• 26-inch height (must clear 28� cabinet ceiling)
• 4-inch diameter bubble plate

Thanks very much!

Lets assume 8" for the collection cup and around 5" for the bubble plate height. That leaves you roughly 13" of reaction area.

A 6" diameter body is rather narrow for a skimmer that short. You will be very limited in the size of recirc pump and air that the skimmer body will accomodate.

You need to be looking at a much wider body for a skimmer that short. You stated system size is 100 Gallons.

I hardly think that scaling that skimmer down to those dimensions illustrates the "perfect" skimmer as outlined in your first post of this thread... not to mention nowhere near "price is no object"

I would imagine that hahn would agree. SKINNY skimmers need to be tallk. The height is what creates the calm reaction area and dwell time.

[JCTewks]

I don't think you are going to get an answer on a skimmer that will remove CDOM's. I don't think there is one out there.

As to Hahnmeister's skimmer design: the height is what will make it an extremely effective skimmer...If you reduce that to 26" totalheight, well, you just built yourself a BM160! IMO you are NOT going to find a skimmer (if one exists) that will skim CDOM's that will be short and pretty. any skimmer that might get the job done will be TALL.

[pjf]

You are correct about the height constraint. It is definitely a compromise. I may consider placing the skimmer outside the cabinet but I would like to take the in-cabinet design as far as it will go first.

The flow rate through the skimmer (75 gph) and the diameter of the bubble plate (4") and body (6") is loosely derived from Escobal's sizing charts (http://www.hawkfish.org/snailman/skimmer101.htm) for a 100-gallon system.

Do let me know what those dimensions should be and why. Thanks!

[JCTewks]

those cimensions sound spot on for a system your size....all i am saying is that it needs to be taller. If the skimmers that currently exist on the market that meet those specs and only have 16-20" reaction chambers don't remove CDOM's...why would one that you build be any different...just buy a bubblemaster if you want that. I think if you want any chance of removing the elusive "gelbstoff", or at least having a chance at the "2 minute dwell time" you will have to have a much taller skimmer.

you just can't get that kind of "dwell" in a 26" total height skimmer...even with the bubble plate. having the slow flow and a recirc design will get you lots of bubbles in contact with the water and follow the "quickly stripping the surface scum" idea that you described. but it will not allow for one bubble to exist in the skimmer body for more than 20 seconds or so. you need the tall height so that 1 bubble can remain in contact with 1 protein for the longest time possible for that "stubborn" protein to have a chance at actually attaching to the bubble.

edit/ammendum: a tall as you can would be best. If you can find a place to hide a 48"skimmer next to the tank, go with that...if you can do a 6' or 7' or 8', go with that. the goals you are trying to reach can only be helped by a "the taller the better" line of thinking.

[BeanAnimal]

Escobal recommends at least 4 feet to 5 feet tall for the reaction chamber to optimize contact time...

...Fossa and Nilsen in The Modern Coral Reef Aquarium volume #1, page 259 recommend that the skimmer reaction chamber should not be any shorter than 28 inches to 32 inches "except for very small aquaria"

The short and fat recirc skimmer is an attempt to rememdy this.

According to Escobal, the upper limit of the amount of air able to be inside the skimmer at any one time is 13% of the water volume inside the skimmer. Escobal does take the reader through the calculations on why this is the uppere limit...

Less air, means less skimming per timespan. Again, short and fat are the answer if height is not available.

There are two keys to injecting air into the skimmer for optimum nutrient export:

1. Keep the air bubbles as small as possible
2. Minimize turbulence of the air bubbles in the skimmer reaction chamber

• Skinny recirc skimmers have a LOT of turbulance to deal with.
• The taller the skimmer the smaller the bubbles due to pressure (does it make a difference... who knows

Are two small skimmers in series better than 1 fat skimmer of the same height?

I would suggest using the largest diameter skimmer body that you can fit in your chosen skimmer area.

The next question: Why not purchase an ASM, OCTO or other similar skimmer that is already built and rather inexpensive. You can get the same basic features and not have to buyild anything. You can MOD the recirc pump with mesh if you like.

Most of us DIY skimmers that we can not afford to buy or that are NOT available for a reasonable price in the size that we desire. If I had a stand that I had to stuff a skimmer in, I would just purchase one ASM, Euroreef, BK or something.

You did say that price was not an object. I think that you can get one hell of a nice BK skimmer to fit in your stand that will almost certainly outperform a scaled down version of the hahnmeisters design (which is meant to be tall and calm).

[BeanAnimal]

those cimensions sound spot on for a system your size....all i am saying is that it needs to be taller. If the skimmers that currently exist on the market that meet those specs and only have 16-20" reaction chambers don't remove CDOM's...why would one that you build be any different...

Exactly

[BeanAnimal]

those cimensions sound spot on for a system your size....all i am saying is that it needs to be taller. If the skimmers that currently exist on the market that meet those specs and only have 16-20" reaction chambers don't remove CDOM's...why would one that you build be any different...

Exactly

[pjf]

Okay.

I believe that per Escobal's guidelines, my skimmer should be the same height (48") as Hahnmeister's design but narrower (4" diameter bubble plate, 6" diameter body) to fit my 100-gallon system.

Should its counter-current flow allow it to outperform the co-current flow of the BK-160 or BK-180?

[BeanAnimal]

That would work much better than what you originally proposed.

You have almost doubled the reaction chamber height. I am not sure if would outperform the BK units.

The counter current flow is not that important for a recirc skimmer (IMHO). There have been some threads that we have tried to hash out the differences betwee CC and recirc, but it ends up being a lot of speculation and very little proof either way.

The thing to remember is that the BK units have a lot of R&D behind them. Your DIY unit will need a significant amount of tweaking. The question of performance is hard to answers (I think the bulk of this thread is evidence of that).

If I had the cash, I would buy the BK
FWIW the turboflotor skimmers also appear to do VERY well.

I DIYed my skimmer because I could NOT afford the tall turboflotor and felt that I could build something that would suffice. I also had planned on doing a CC airstone unit, but as mentioned, changed the plans due to complications with regard to airstone maintenance.

[pjf]

Hahn's recirculating design is a bit different. The water between the two cylinders is collected, mixed with air, and pumped to the bottom of the inner cylinder. The air-water mixture is prevented by the inner cylinder from immediately returning to the needlewheel. The recirculation mechanism here simply takes the place of the airstone. Since the air is introduced at the very bottom and since the water is introduced just under the cup, there is a true counter-current flow.

In contrast, the 4-foot Turboflotor 5000 "Baby" has less than a foot of counter-current flow. The water inlet and the air inlet are very close together (http://www.aqua-medic.com/turboflotor_5000.shtml).

So we're not sure if this gravity-fed, counter-current, recirculating design can beat the sump-fed, co-current, non-recirculating BK-160 or BK-180? There must have been some serious R&D at Royal-Exclusiv?! This is when I wish the Penn State skimmer researchers would hurry up!

[BeanAnimal]

The only major difference between my design and that of hahns is the water inlet position. I also used an inner mixing chamber.

If you notice, some of the water entering the skimmer can directly shortcut to the output after 1 CC pass. In my design the water is forced through at least one circulation loop and up into the skimmer body, at least one time. is there a difference? I dunno.

If you observe a recirc skimmer in opperation you will notice that the bubbles along the outside circumferance of the chamber are flowing downwards. The air/water in the center of the column flows upwards and displaces watere at the top of the skimmer, where it flows back downwards (counter current).

Remember the FEED flow is much less than the recirculation flow. The recirculation flow not only takes the place of the airstones, but it moves A LOT of water.

In contrast, an airstone skimmer only moves bubbles and the water that is dragged along with those bubbles.

Both skimmers create a counter current in one form or another.

[pjf]

Unlike most recirculating systems, the flow in your tower is symmetric: upward flow in the center and downward flow along the sides. Your mixing box and inner cylinder isolates turbulence from the rest of the tower. The direct pump feed ensures every drop goes into the meshwheel. You've made lots of improvements. Three questions:

- Is anyone marketing a skimmer similar to yours?

- How do you size the meshwheel pump to ensure that the air-water ratio meets Escobal's 13% guideline?

- With a direct overflow feed into the meshwheel pump, does it matter if you do not purge the bubbles from the feed?

[BeanAnimal]

I am not sure that anybody is using the same exact concept in a retail unit. I am not even sure that I am the first person to incorporate those ideas in one skimmer. I am also not sure that it is the best overall design. It was an adaption from my CC airstone design.

The pump sizing was a guess. Larger pumps can process much more air, but also produce much more flow and turbulence.

As for the 13% several of us (TinyGiants did most of the grunt work) worked on a spreadsheet to calculate the air to water ratio in the skimmer. I have NOT calculated mine, but am rather sure that it is far below 13%. The OR3500 needlewheel is choking at between 22 and 30 SCFH of air. I should be able to get twice that into this skimmer body.

Feeding bubbles into the recirc pump should be fine. My skimmer is so tall that it must be force fed with a minijet 606 from my overflow box. I am sure that some bubbles get pushed in.

The box has created some problems that had to be overcome. The air bubbles that found their way into the box were collecting and then violently burping up through the body. I had to reconfigure the recirc pump intake to draw the water from right under the bottom plate and keep the bubbles from forming and burping.

[hahnmeister]

I never understood that whole 13% idea. Well, I understood IT, but I didnt think it ever held up. The ideal air throughput of a skimmer isnt based on volume, it is based on lph per body area. 22-30 scfh of air on a 6" diameter body... well... it doesnt get much better than that. 35.3/1000lph is the max for 6" diameter really. More than that, and the bubbles start to get too violent themselves.

[burris]

I believe the total surface area of the bubbles inside the skimmer is what is paramount. If you pumped 1000lph of air through a 6" skimmer by just sticking an air hose into it, not chopping up the bubbles, it wouldn't skim very well, would it?

[pjf]

Originally posted by BeanAnimal
The only major difference between my design and that of hahns is the water inlet position.

Your inlet placement avoids a lot of problems. You don’t have to worry about the height of your gravity feed since you’ve lowered the inlet. You don’t have to worry about turbulence at the inlet since you are directly feeding your recirculating pump. Do you need a siphon break on the drain line to the sump?

There are more differences. Hahnmeister would have to do the following to match the type of flow in Bean’s skimmer:

• Lower the inlet to the bottom
• Lower the drain to the bottom
• Reverse the recirculating pump flow
• Inject the air-water mixture into the inner cylinder
• Move the bubble plate to the top of the inner cylinder
• Close the bottom of the inner cylinder
• Drill a ring of holes in the bottom plate

Hahn’s design has counter-current flow but perhaps more turbulence at the water inlet (halo spray collar?) and at the inlet of the recirculating pump. Bean’s design eliminates turbulence in the tower.

Does anyone have predictions on their relative performance?

[BeanAnimal]

The skimmer is fed from the overflow via the minijet. It also returns to the overflow (on the other side of the standpipes). During a power outage the skimmer level only drop 8 inches or so.

The original plan was to feed from the overflow and return it to the sump. I was afraid of a runaway situation, even though my setup should be capable of self tuning around it.

The next plan was to feed via the input chamber of the sump (outby side of baffles) and return to the inby side of the baffles. This posed a problem with the backflow during a power outage. 15 extra gallons in the sump from the skimmer would be bad news.

So my design is mostly a product of necessity. It just turns out that it works well too!

I would not hazard a guess as to which skimmer would perform better of they both had the same body diameter and height. I would bet they would be close. The height being the important part. I would also submit that the pump itself would be a major factor. Smaller bubbles with LESS flow are the goals.

[BeanAnimal]

Hahn, have you looked at the spreadsheet? The 13% number is pretty hard to achive.... I don't think even the dart NW thread saw numbers above 12% or so. I could be wrong.

Have you read the Escobal explanation of the 13%?

[Fishbulb2]

i've read it also and made a similar spread sheet. I calculated what I would need for my RS100. No way I was going to get that much air into it. I wanted to buy a luft pump to pump that much air into the skimmer. There's no way that would have worked without the pump cavitating.

[BeanAnimal]

I purchased the Escobal book used for a hefty price. I can not find it for the life of me. The warden likes to collect things around the house that she thinks are no longer needed. I suspect it went the way of my green suede Vision skate shoes and the others things she has deemed clutter and irrelevant. I suppose one day it will be me that gets tossed....

[pjf]

Originally posted by BeanAnimal
You did say that price was not an object. I think that you can get one hell of a nice BK skimmer to fit in your stand that will almost certainly outperform a scaled down version of the hahnmeisters design (which is meant to be tall and calm).

OK. We can come back to the ideal DIY skimmer.

Which retail skimmer is best for a 100-gallon system with a 30-inch cabinet stand (28" interior)? You say Bubble King (Mini?). Hahn says ATB cone (small or nano). They don't look like anything P. R. Escobal would design. They seem "out of the box."

The test results aren't in but what are their design strengths and weaknesses?

[BeanAnimal]

I have heard very good things about the BK skimmers, even though the price is very high. I have also heard good things about the ATB. Folks love their ERs etc.

I would be apt to say that they are not ideal skimmers compared to a similar design that is scaled to a 4', 6', 10' or whatever height.

When you can only consider what will fit within your space and budget constraints. Thay may mean running carbon to remove the yellowing compounds.

Don't get me wrong, I understand your desire to test and to have every skimmer down the pike ranked by that meaningful test. The same can be said about Tires, Amplifiers, Refrigerators, Beer, or anything else that is subject to varied environments, tastes, etc.

This is where informed opinion and observation help us wade through the options. Sometimes were get lucky and ward off buyers remorse for another purchase on another day

[JCTewks]

IMO, you will get better performance, and better ovarallDOC removal (esp more of the moresoluble DOC's) with a well designed very tall skimmer.
If you are only going to be feeding 75gph theough the skimmer, i don't think you'll see much in the way of added turbulence. Personally, I would build a skimmer similiar to either bean or hahn, but throw a wet neck on it and do 100% of your feed water down the wetneck. Every drop of feed water would have to fight it's way through everybubble ion the skimmer to reach the output.

As to the co-current vs counter-current...I remmber reading in bill wann's old tank thread that he switched to a top feed from a bottom feed and the skimmer performance went up considerably. There was more turbulence in the body, but it was on a 1500gal tank. Bill said that the added turbulence was woth it for the greater improvement of the skimmer.

But, really, you're only putting 75gph through it...just run it in through a wetneck...plus you get the bonus of the original purpose of a wetneck...a clean neck

[pjf]

That is a good idea! For a small system with 75 gph of flow, the inlet may just as well be the wetneck.

Where does one get exotic skimmer parts, such as:

• Halo inlet spray collars
• Wet-neck inlets
• Zero-clearance collection cups
• Tapered neck flanges
• Pipe connectors for cylindrical walls
• Eheim or Sicce pumps with thread or needle wheels?

The wet-neck or "halo" spray collar will help with symmetric flow at the inlet. The zero-clearance collection cup will gain a few inches of reaction height.

If you have links to detailed wetneck designs, that will be great!