Skimmer

[getwet]

Looking at a skimmer for a large system I'm planning this summer. I'm kind of limited on hieght to maybe 80" (that's 200 cm to the rest of the world).

Anyone with numbers or experience with the smaller RK2's or the larger ETSS?

[MAS]

Ive got experience with ETSS and run a custom RK2 currently. I was never impressed with ETSS skimmers, for the money paid out there are just too many other skimmers that pull out organics just as quick with much better efficiency. As for the RK2, they are OK for the money. I just got a custom one in a few weeks back, its a basic venturi setup with a washdown feature that doesnt work as good as I expected. With that being said I will probably be converting back to the Euro-reef skimmers. THe 12-6 would fit the bill for you nicely or you can wait for their new 18(18" diameter) series skimmers which is going to use a single external needlewheel pump vs. the multiple Sedra's they currently emply.

[anthem]

Don't even bother with RK2 if you're height limited. They aren't good until at least getting into the 25 or 35. The 25 is for all intents and purposes their entry level line. The shorter one that they make (the 15 I think), is not really worth it. Basically the RK2 is a great unit if you're going to push about 1/4hp pumps worth of water into the unit. If you can do that (9.5' units), then the Rk2 unit is excellent.

If size isn't an option, then go with a large beckett based skimmer (MTC, Precision Marine, etc), or a euroreef. What they don't have is the long contact times that size can give (+ recirculating).

Ed

[MAS]

Ed, Im going to have to disagree somewhat to part of your statement. Euro-reefs do make recirculating models and have excellent contact time(as do all slow flow needlewheel designs)regardless of height of skimmer. Beckett skimmers though dont have long contact time since their design is based on how much water and air they can push through the reaction chamber, which is a completely different thought on skimming altogether.

[getwet]

Thanks for the advice, I'll check out the Euro Reefs. I was looking at the RK2 25....it's right about the maximum height I can use, the problem is I would prefer the 35.

I was wondering about the ETSS contact time. I'm surprised more skimmers don't list their throughput and contact time, as no matter what your method of injecting air, that defines your capacity.

[JRF]

HI,
Check out www.reefconcepts.com , Frank has great skimmers for large tanks and can custom make any size you may need even bigger. Quality is excellent !!
JRF

[KenT]

I run an Aerofoamer 848 on my 700 gal capacity system, and am very pleased. check out their site. www.reefconcepts.com

[KenT]

JRF, you owe me a beer!:beer:

[SPC]

Hi Ken,

Do you know of any differences between the Aerofoamer and the PM becket styles (Bullet) that you could share. I am in the process of trying to decide on a skimmer for my new 450 gallon system.
Steve

[JRF]

I hear ya KenT !
SPC, My suggestion is to go with the Aerofoamer. The Aerofoamer uses a nice becket and a newly designed injector housing. Call Frank and he can give you any specs you may need on his skimmers. He lives only 10 minutes from me. I have been to his shop and seen some of his building process. He is very detail oriented and I'm serious about the quality ( and customer service ) of his products, totally superior to anything I have seen.
JRF

[saleencobra]

When choosing a skimmer is it best to go on total gallons in your system or in your just in your tanks?

[JRF]

Go with total system gallonage. Depending on what you want to keep in your tank determines how much skimming you will need. I always opt for heavy skimming. My system volume is about 370 gallons, my skimmer is rated for up to a 2000 gallon tank ( with appropriate pump ).
JRF

[MAS]

JRF: And what skimmer are you using thats "rated" for 2000 gallon system? I have NEVER seen a skimmer mfg.(this includes Aerofoamers,PM,ER,ETSS etc etc) that didnt grossly exaggerate their skimmers tank rating capacity. Best thing to do is look over the physical dimensions/thruput,air input/dwell time etc etc of the skimmer and pump combo in question.

[saleencobra]

If you dont mind me asking, how much would one like yours set me back?

[JRF]

I'm not sure of the prices now , I think they are priced on the web page: www.reefconcepts.com
MAS, my comment wasn't meant to be a technical study of skimmer opertion I was just making a general statement. You are definatley correct. If you look on the web page above you will see the 848 model I use. Actually I should have said that this particular skimmer is "rated" for 200 - 2000 gallons depending on the pump size running the skimmer. I do not know how those numbers were measured. There are definately variables that come into play depending on a particualr system and the amount of skimming needed/desired. The pump I use on the 848 turns over about 5 times my system volume. I choose this skimmer so I could easily run that much volume through it , as well as the long dwell time of air/water contact which corelates to the physical diameter and length of the riser tube. If you have concerns about how the skimmer is "rated" I recommend you contact Frank at reef concepts and ask him how he comes up with that number.

[KenT]

SPC,

I do not know much about the Bullet. I think however that it's air induction is slightly different than a becket. Have you checked their web site?

[MAS]

Yes, I am familiar with reefconcept products. But in noway would I use an 848 for anything over 500-750g(assuming you can pump a real 1500 gallons through 1 injector which is kind of far fetched with most pumps to begin with) of water on a moderatly to heavily stocked system with a 1 injector beckett skimmer.On your 300g though Im sure its fine. What pump are you using btw?

As for how they rate them, I believe most beckett mfg. use the maximum tank rating as the maximum water they can pump through the skimmer per hour equal to a single turnover. But I would never want my skimmer to only turn over the total volume once per hour. Skimmer mfgs. should realistically rate the maximum rating on their skimmers for a minimum of twice the total turnover volume(ie: 1000g throughput on a skimmer would mean a tank of 500g would be the maximum), but I personally feel around 4 times turnover is a better, much more realistic rating, but then some mfg. may be hurting a bit in sales due to conservative numbers quoted.

[anthem]

Originally posted by MAS
Ed, Im going to have to disagree somewhat to part of your statement. Euro-reefs do make recirculating models and have excellent contact time(as do all slow flow needlewheel designs)regardless of height of skimmer. Beckett skimmers though dont have long contact time since their design is based on how much water and air they can push through the reaction chamber, which is a completely different thought on skimming altogether.

Mas, you can disagree all you want. The reality of the situation is that you can pick whatever technology you want, but after that size plays a very important factor. You can take the 12-6 and yes its a great skimmer and has good contact time for comparison with other skimmers that are about that size. You compare it to the PE35 from RK2 and its really no comparison (and there are larger ones). That unit is about 9ft tall and 18" in diameter for the reaction chamber itself. Sheer volume says that its reaction chamber is about 3 times larger than the EuroReef. The contact time with most skimmers is measured in seconds to 30 seconds, the RK2 has a 1:30 to 2min contact time rating. . So its really not about knocking euroreefs as I own them as well, but comparing it against an excellent 10ft skimmer is foolish.

Also, doubtful that the RK2 units are 'over rated' for their capabilities. . .

Ed

[MAS]

Ed, actually there is no RK35 unit currently, maybe your referring to an RK50? And my comparisons are based on the RK25 which is 79" in total height, 7" of which is just plumbing on the top of the unit. SO comparing a skimmer such as the RK25 to a CS12-6 will garner a much different result as both skimmers are of equal size. If this is a CS12-6 EXT recirculating model then I would take the ER any day of the week though no doubt. I currently have a unit from each mfg.

If you want to compare an RK50 to the new CS18 units that are due out soon, then again we can have a comparison done on a fair playing field where reaction chambers are similiar in dimensions. BTW are you aware that Euro-reefs can also be ordered in taller spec'd setups with or without recirculating(EXT designation) abilities?

[wetworx101]

Just a note, JRF, I think you really want to calculate the skimmer according to just the tank gallonage. Lets say you have a 200gallon, and another 300gallons in sump systems. Why would you bother with a 500gallon skimmer as there are only 200gallons worth of critters making waste? I have a 60cube with a total system gallonage of over 200gallons (plenum, sump, fuge). Now, getting a skimmer rated for 200gallons would just strip out too much and do more harm than good, no? I only have 60 gallons worth of fish and corals after all.

[KenT]

[QUOTE]Originally posted by MAS
[B]Yes, I am familiar with reefconcept products. But in noway would I use an 848 for anything over 500-750g(assuming you can pump a real 1500 gallons through 1 injector which is kind of far fetched with most pumps to begin with) of water on a moderatly to heavily stocked system with a 1 injector beckett skimmer.On your 300g though Im sure its fine. What pump are you using btw?

Who said the 848 can only be used with 1 beckett? There are several skimmers that use more than 1 for that matter. I drilled a second 1" bulkhead in my 848 and hooked another Iwaki 100 to it, without an injector. The single beckett powered by an Iwaki 100 + another 100 is pushing 2500+ gal/hr. Water column was saturated with tiny bubbles. I recently added a 1" Mazzie venturi to the 2nd 100 to see if the added air would make a difference. I haven't noticed any increase in foam production or scum. My system has a heavy load. I would say that this skimmer could handle a much larger system than you suggest.

[MAS]

Who said the 848 can only be used with 1 beckett? There are several skimmers that use more than 1 for that matter. I drilled a second 1" bulkhead in my 848 and hooked another Iwaki 100 to it, without an injector. The single beckett powered by an Iwaki 100 + another 100 is pushing 2500+ gal/hr. Water column was saturated with tiny bubbles. I recently added a 1" Mazzie venturi to the 2nd 100 to see if the added air would make a difference. I haven't noticed any increase in foam production or scum. My system has a heavy load. I would say that this skimmer could handle a much larger system than you suggest.


KenT: The 848 comes STANDARD with 1 single injector, and Im well aware of the fact that many beckett skimmers do have more than one injector. Even if you added a 2nd injector of some sort, the reaction chamber(which is pretty small to begin with)still remains with the same volume, and you in theory have just cut bubble dwell time in half at least since you've potentially doubled(or more since the 2nd Iwalki doesnt have the same back pressure as the one hooked up to the beckett) the output. So your getting a higher thruput, but are sacrificing bubble dwell time at the same time. So skimmer performance isnt necessarily any better after all that modification.

[SPC]

Originally posted by JRF
I hear ya KenT !
SPC, My suggestion is to go with the Aerofoamer. The Aerofoamer uses a nice becket and a newly designed injector housing. Call Frank and he can give you any specs you may need on his skimmers. He lives only 10 minutes from me. I have been to his shop and seen some of his building process. He is very detail oriented and I'm serious about the quality ( and customer service ) of his products, totally superior to anything I have seen.
JRF

Thanks JRF, I'm still doing research.


Originally posted by KenT
SPC,

I do not know much about the Bullet. I think however that it's air induction is slightly different than a becket. Have you checked their web site?

Thanks Ken, I am in the same type of situation as you, I've seen the Bullet in action but have not seen the Aerofoamer running.
Steve

[getwet]

Sorry... I followed someone else's lead. It's the RK2 RK-30 not 35.

It may just be time for a small shed with a 12' ceiling.

[KenT]

Even if you added a 2nd injector of some sort, the reaction chamber(which is pretty small to begin with)

I'm not sure what you mean by saying the reaction chamber is small. The 848 has a 10" diameter and is 48" tall. I will admitt that I have not studied the lenght of bubble contact time or the volume these skimmers can handle. I would like to know where you get your info.

Skimmers can be argued all day long since nobody really knows the optimum amount of flow through a skimmer, bubble contact time, amount of bubbles, if a short fat skimmer is better than a tall thin one, etc. etc.

I can speak of my experience though. My heavily loaded 700 gal system is thriving. I do water changes at a min. of 2 month intervals.

To be perfectly honest, I don't even know if my skimmer does anything at all! I have never been without one on my tanks. Maybe I will shut it down for a while and see what happens.

[anthem]

Originally posted by MAS
Ed, actually there is no RK35 unit currently, maybe your referring to an RK50? And my comparisons are based on the RK25 which is 79" in total height, 7" of which is just plumbing on the top of the unit. SO comparing a skimmer such as the RK25 to a CS12-6 will garner a much different result as both skimmers are of equal size. If this is a CS12-6 EXT recirculating model then I would take the ER any day of the week though no doubt. I currently have a unit from each mfg.

If you want to compare an RK50 to the new CS18 units that are due out soon, then again we can have a comparison done on a fair playing field where reaction chambers are similiar in dimensions. BTW are you aware that Euro-reefs can also be ordered in taller spec'd setups with or without recirculating(EXT designation) abilities?

Rk2 has actually renumbered their skimmers (twice in the last few years). I think their 79" is pretty much useless as its their entry line model and yes I wouldn't bother. The next model up used to be the 25 which is now the 30(which before used to be the 2400), and the 35 is now called the 40(and used to be the 3500.

If you're comparing a as yet to be done ER 18" x 9ft+ model against the RK2-40's 18" model then you might have a fairer comparison, but remember I wasn't talking about fair in my original post. I said if you weren't going to use the 15/18" x 112" models then don't bother with them. I'd go with an ER or some other skimmers as well. The entry level skimmers just aren't worth it. I have ERs as well as the aforementioned 18" RK2 so I know them well.

[anthem]

For all of you people arguing that more beckett heads are the solution, it isn't. Yes, more beckett's allows you to turn the water over more, but its only useful if you can maintain bubble/dwell/contact time. Since as MAS indicated earlier, that you are essentially halving those parameters by shoving twice as much water through the same volume, you are losing efficiency (presuming that it was developed and can be adequately driven with a single beckett). Now, if the unit can't be adequately driven by one beckett and was designed for two, then it needs two and it was built into the equation. But converting a single beckett to dual because it's 'cool' is not so 'smart'.. . ..

Assuming bubble creation are equal as its very very difficult to say any one method of bubble creation is better than another, the single most useful thing after that is volume (obviously how it uses that volume is important as well but volume is it). A larger volume skimmer on the same input gives longer contact/dwell times and that is the primary measure of effectiveness of a skimmer. It's also the main reason why no matter how hard you argue, a much larger skimmer with the same ratio of water/volume flow will outperform a smaller skimmer (an ER 12-6 will outperform a ER12-1), regardless of size of tank.

[MAS]

KenT: Actually the diameter on the 848 is 8", unless they made a change recently that I dont know about. But no biggie either way.

The optimal "flow" through a skimmer is pretty simple though. THe longer the bubbles stay in contact with the water, the more waste they can extract, its that simple. There is a point though where the trade-off between dwell time and water throughput will be optimized of course. But with most high speed injection units, dwell time is sacrificed for water process per hour. There was a great article a few years back that pitted an Aerofoamer,Euro-reef,ETSS and an AquaC model head to head. The Aerofoamer and Euro-reef models marginally had the best waste removal abilities in the shortest amount of time. THe EUro-reef though was able to do the same job as the Aerofoamer only processing about 1/3 of the water through its mixing chamber though.

This just shows the 2 schools of thought. Both schools work, one does it quite efficiently(Euro-reef only used about 1/8th as much electrical consumption)as the needlewheel design proved, while the other(Aerofoamer)used brute force via a relatively large pump(Mag 24 I believe)by jamming as much water an oxygen together.

As for shutting down a skimmer, I dont think that test is necessary. I know a few people like running skimmerless, but I feel its an integrated part of a system's health and is vital to help oxygenate the water in our systems which sorely lack water movement and surface contact compared to the open reefs in nature which have millions of gallons washing over them every hour. Were lucky if we can turn the water over a few thousand times per hour. But of course that is a whole discussion onto itself.

My water changes seem to take place around the 6-9 month interval, but I would like to stretch that to 12 months on my new system setup.

[MAS]

Anthem: Didnt realize you were basing an argument on an "unfair" comparison, my bad! =) But it looks like we are both on the same page regardless! Good show!

MAS

[myreef]

The problem with running two beckett injectors on a skimmer is that people want to use two pumps with it. This indeed does nothing for you. You can actually run the same single pump and feed two beckett skimmers and get more air into the skimmer and flow the same water. By cutting the pump in half and feeding two becketts you are allowing more bubbles that can be fine tuned smaller. This will give you more contact time, since there are more bubbles. We have done extensive research and testing. If you add two becketts or more (we have made up to 4) we increase the box size to offset what is talked about above. Some of the skimmer boxes we use for dual and more becketts range from 12x12 to 16x12x12 and even 20x12x12 for a 4 beckett skimmer. We are making a skimmer now that will be 8 feet tall quad beckett with 2 2" gate valves. It will be using a 2 HP pump (10000 GPH). Trust me in these extreme situation, you are getting plenty of turn over. Also, a beckett skimmer is only limited to 1 factor...can the gate valve keep up with the water coming in. If it can you can run as much pump as you want through the beckett get more air and bubbles and skim what you want.

SO I guess this long winded post was to say...2 becketts same size box is better if you know the correct pump to use....

[KenT]

MAS, I appreciate that response. Now we're getting somewhere!

There is a point though where the trade-off between dwell time and water throughput will be optimized of course.

You hit the nail on the head with that statement! Now, what is that magic relationship? And where does it lie with individual skimmers? How can this be determined? How do you figure out the optimum turnover rate for optimum contact time?

[anthem]

Andy, I agree with you that running two becketts is better than one assuming the same water turnover rate and additional bubbles. I don't think the relationship is linear though. Having two becketts isn't a doubling of capability though, its a incremental improvement (more than marginal, but less than linear). I still think

Now in terms of real efficiency, I think reaction tube size plays a larger part in better skimmers.

I won't get into beckett vs needlewheel though as that's more of a religious debate. Also, there was a recent discussion of how much the ER pump really draws that no one actually finalized. Anyhow, its apples/oranges. The only thing I'll say is that regardless of technology, size of reaction chamber rules.

[MAS]

Which ER pump are we talking about. With the Sedra 5000 I get a max load of about .3 amps. About .7 from a Sedra 9000. I dont think anyone will complain about that draw......

[MAS]

Andy, BTW you've come along way with your skimmers. Your showing alot of ingenuity after all, my hats off to you........

[JRF]

This has become quite a discussion! MAS, you are indeed correct about the injector. The 848 can be outfitted with another injector if needed/wanted. I am using an Iwaki 100 with the 848 which is probably only getting about 900 - 1000 gph through the becket.
Wetworx101, the way I see it is that it's the same water in the system so the skimmer should be matched to total water volume, sump, fuge and all. Although, I do see what you are saying. I guess its up to each individual to determine the best approach for their system.
SPC, good luck and I still recommend the Aerofoamer.

[myreef]

Originally posted by MAS
Andy, BTW you've come along way with your skimmers. Your showing alot of ingenuity after all, my hats off to you........

Thanks...I think....back handed compliment, but I will take it. :p

Originally posted by anthem
Andy, I agree with you that running two becketts is better than one assuming the same water turnover rate and additional bubbles. I don't think the relationship is linear though. Having two becketts isn't a doubling of capability though, its a incremental improvement (more than marginal, but less than linear). I still think

Now in terms of real efficiency, I think reaction tube size plays a larger part in better skimmers.

I won't get into beckett vs needlewheel though as that's more of a religious debate. Also, there was a recent discussion of how much the ER pump really draws that no one actually finalized. Anyhow, its apples/oranges. The only thing I'll say is that regardless of technology, size of reaction chamber rules.

I agree...The larger skimmers we make use 8" tube and will be coming out with some 12" and larger skimmers soon. I do like large skimmer boxes on larger tubes for sheer volume of water in the skimmers and allowing more air into the skimmers "sump" and ultimately up the riser tubes.

Having 2 or more becketts does not make the skimmer be able to double the rated volume. Our single MR-2 can easily skim 250 gallons, but with an additional injector, it can skimmer 350-400. I have run a dual beckett MR-2 on my 500....under powered, but still did a good job.

The tube and skimmer box needs to be proportional...I think a lot of people miss that point. A 8" tube, IME, needs a larger skimmer sump than 10"...that is why we use 12x12 as a minimum for such a skimmer...yes it takes up space, but .....well you get the idea.

Good discussion!

[bernie lyons]

Hello all
I own and have lived with some of the best skimmers and
depending on your preference(long contact time)go with either a large venturi or an Deltec AP-1006 which produces the smallest
bubbles with excellent contact time.But if you prefer high turnover per hour basis then go with an MTC HSA-3000 dual beckett
it needs an Iwaki -100RLT pump for maximun performance
cheers-bernie lyons

[andycook]

Does the popularity of the super big skimmers with water pushed by super big pumps mean that the principles articulated in Escobal's book are out of favor?

[MAS]

Thanks...I think....back handed compliment, but I will take it. Actually its an honest straightforward compliment. I chided you pretty bad a few years back on "cloning" PM skimmers, but after watching your product develop and grow, I would have to say your in the forefront of the beckett skimmers. I like what you've done with em alot. PM and Reefconcepts and MTC(I actually carry the MTC line) really havent shown any growth or development the last few years and I have found alot in each design that could very easily be improved upon. But your products continue to grow and develop in a positive way. If they look and function half as good in person as they do on the website, Im sure I would still be impressed. Take the compliment, I dont give em out lightly these days. :D

cheers
MAS

[SPC]

Originally posted by JRF
SPC, good luck and I still recommend the Aerofoamer.

Thanks JRF, and thanks to all for such an informative discussion:) .

I have what is probably a stupid question, but here goes anyway:D . What would happen if a needle wheel was run on a beckett skimmer?
Steve

[KenT]

SPC, I'll add to your question. Are skimmers designed around the type of induction? Does a beckett skimmer perform better than if it had a venturi hooked up?

[Diatom2]

Originally posted by SPC
Thanks JRF, and thanks to all for such an informative discussion:) .

I have what is probably a stupid question, but here goes anyway:D . What would happen if a needle wheel was run on a beckett skimmer?
Steve

I had the same thoughts when reading this thread, then my feeblemind decided that since one is based on brute force and the other on longer contact time that there isn't much to gain in the combination. Now lets see what someone who knows something has to say :)

[T Sandman]

I doubt that a needle wheel impeller pump can produce enough pressure to run a beckett eductor optimally.

Another factor to consider (which I suppose should go without saying) is bubble size. Water quantity and dwell time don't mean much without a proper size and amount of bubbles.

In my opinion the best skimmers have a pump that draws from and pumps into the column. I know there is a commonly accepted name for it. I'm rusty on all my lingo. I think this type of skimmer can be tuned to be more efficient than any skimmer that utilizes a pump to only pump through it.

Good luck on your hunt.

[bernie lyons]

Hello folks,
A couple of comments on this latest address of skimmer performance.First a mention of Escobal's book,referencing about turbulence (not desirable) to produce a stable foam without breaking the seperation process.And using a recirculating technique to produce a more thoroughly dense column to maximize air/water contact .These methods are not new,but amazing enough ,everybody is still trying to reinvent the wheel all over again ! The point here is that despite the latest in technology I think the good old fashion air driven counter-current skimmers still teach us the basic's of extracting the most unwanted crap from our systems!!!cheers-bernie lyons

[RedEyeReef]

Just following along this great discussion... someone who has and likes both Becketts and Needle wheel skimmers.

[T Sandman]

Originally posted by bernie lyons
Hello folks,
A couple of comments on this latest address of skimmer performance.First a mention of Escobal's book,referencing about turbulence (not desirable) to produce a stable foam without breaking the seperation process.And using a recirculating technique to produce a more thoroughly dense column to maximize air/water contact .These methods are not new,but amazing enough ,everybody is still trying to reinvent the wheel all over again ! The point here is that despite the latest in technology I think the good old fashion air driven counter-current skimmers still teach us the basic's of extracting the most unwanted crap from our systems!!!cheers-bernie lyons

I totally agree. I loved my cc airstone skimmer. The biggest gripe with them is having to change the stones which is why we have the injector debate. But when they are working, boy look out! Here comes the foam!

[Zephrant]

I do have one minor nit about Escobar's book. I'm left with the feeling that he carefully engineered the perfect skimmer yet did not properly define the starting point.

Where did he come up with the "turn over 99.8% of the system water twice a day" number? It would appear that a number like that would need a ream of scientific information gleaned from detailed studies by Marine Scientists. Instead, he throws it out as "sufficient" with no background support what-so-ever, then proceeds to design a skimmer that meets that goal.

I have no issues with the formulas and physics he provides- It is pretty straight forward. I do question his starting premise however. Keep in mind that his book was written before the ETSS design came out, and way before the Becketts landed on the scene.

I agree the that Beckett and even the down-draft style skimmers go for a lower efficiency (measured in % of contaminants removed per pass), but I feel they make up for it by having more passes though the skimmer.

Yep, this costs more in electricity, but you don't need to replace air-stones, and it is a set and forget setup.

Zeph

[dgasmd]

When I started in the hobby, I ahd this 4" diameter and 6' tall CC skimmer. It rocked no doubt. However, too many thing would throw it off. Touching the water would shut it down for hours. Same for feedings. Then, for no apparent reason it would go nuts and overflow. It was a constant battle to get it to just run constantly. When it was running properly though, it was a beast.

I know scubadude had built a huge one out of 6" PVC and was like 10' tlal. He was feeding it with a mag 2 or 3 and had a piston air blower for air. That thing was a rocket and made the beckett skimmer hehad in the system look like children toys.

[anthem]

The old counter current air-stone skimmers are definitely very very efficient in their performance. The main trouble with them was their constant adjustment. That and yes, when their was oils in the tank from food or hands/arms it would take hours to break that down to start up again. The higher pressure pumps today break that down a bit faster than the air-pumps from before. . .

[dattack]

From experience, my friend runs a Euroreef 12-5 with only one sedra pump with needlewheel.
It was a used 12-5 but he didn't want to run all 4 sedras in sump. He opted to place one beckett foam injector which produces tons of bubbles in comparison to one or even two sedra pumps. He runs the beckett with a mak4. This then allows for the only one Sedra pump to recirculate the bubble into finer bubbles which allows for better skimming.