Any ideas for a dcent DIY Skimmer

[coolcol]

Any ideas for a decent DIY Skimmer

My one real desire is to construct my own Skimmer....my one question to any of the scientists out there is concerning the air venturi tube.........
When i have used such a device on say an aquaclear 802 powerhead....the bubbles ceased when the powerhead was submerged about 6-8in ...obviously the suction created by the venturi device on the powerhead was not stong enough to overcome the water pressure at 6-8in.....NOW....
When i use the same feature on my Red sea Berlin skimmer the air line is over 12in long ...well below the height of the water in the skimmer.....this seems true of any skimmer.....some are much deeper than a basic red sea berlin skimmer!!!!
So just How is it possible for the venturi in my Red sea Berlin skimmer to overcome the pressure of water in the deep skimmer?
If i use the same principle as the deltec skimmers would it make any difference were the mixer pump was situated as regards its position on the tube ...is this critical for the venturi to work.
The main priciple is easy.....inlet at the top water flows down tube and as it does it encounters the bubbles produced from the mixer pump situated near the bottom.
Waste water exits from near the very bootom back to tank/sump.
Easy right? ............why pay over $500-1000 for a big skimmer when they are so basic in their construction............whats the catch?
Beats me......if anyone can explain i would be pleased to hear it.....anyway....here is a pic of my proposed Skimmer..any helpful comments or advice on say the type of pumps etc would be appreciated......Colin.

Oh forgot to mention........does anyone have any ideas on a suitable tube...i was thinking of Acrylic or perspex but availability is a problem.....anyone made a skimmer that is not made from either a TUBE or from a different material? or ideas where to obtain such big tubes cheaply!

 

[Zephrant]

The amount of air a venturi pulls in is dependent on the water flow and venturi design. The 802 does not have much of a venturi, so does not have much draw. A good skimmer has a much better venturi, so can still draw air in when it is deeper.

The more draw a venturi has, the more back-pressure it puts on the pump. Nothing is free.

The deeper you place the pumps, the less air they will draw in. That is a balance, and is why you don't see very tall needle-wheel skimmers. They are most efficient on short skimmers, so they are quite often wide as well to increase the volume- Up to 16" dia. in some cases.

If you want to increase you odds of "getting it right" the first time, copy an existing design closely- There is a lot of engineering that goes in to building a good skimmer. I suspect that if your pump is located as shown, it will not be able to draw in air.

For tube- Consider large diameter PVC pipe- Not clear, but far cheaper than acrylic. You can also make the skimmer box square.

Zeph

 

[coolcol]

Cheers Zephrant, The design i have drawn ''IS'' a scaled up Deltec 600 skimmer......I have also looked at ALL the other deltec skimmers and the only notable difference in the Deltec range seems to be related to the size of skimmer tube and number of injector pumps used!

I was hoping to use just ONE pump to inject the bubbles for simpicity and ease of maintainance etc.

Yes I have considered using pvc pipe but the lack of transparency puts me off....call me old fashioned but i want to see how the skimmer is performing so i can fine tune it....a few people have used pvc pipe to good effect but do they really know what is happening deep in their skimmers? No they dont....they may think they have a good skimmer when a simple look inside might reveal some obvious problems/improvements.
Anyway why does the skimmer have to be a tube shape?..does anyone know?

I am certainly surprised at the lack of interest in my post since most people seem to show an interest in new skimmers and their associated new technologies.

There are also some other Diy skimmers designs on this forum from other users but how much did they cost...how did they arrive at their design?....their posts certainly attracted alot of attention as do certain other ones showing comparative tests etc (all good might i add!) and they were certainly very interesting but i didnt find them very informative or explanative in how they ended up with their designs.
Were they just based on their commercial equivalents or some imaginative inspiration like mine!!!

I am looking at a simple way to construct either a tube or box shaped skimmer utilising easy to obtain pumps/pipework etc to produce the most effiecient skimmer at the best price/performance ratio. One design that can simply be scaled up and built by others to save money (unless you lot are happy forking out preposterous amounts of dosh for what at the end of the day are just simplistic tubes with pumps attached!!) these skimmer companies have got us lot just were they want us!...while we continue paying crazy amounts of cash for simple tubes of acrylic with a few tubes glued to them these companies will continue to whet our appetites with successive 'New' design features(probibly discovered by accident by an aquarist somewhere!)

What i want to know is
1./ Why are most skimmers tube shaped?..does anyone know (enough of us use them!)..i dont know...maybe its to do with smooth flow or something...am only guessing here....do you know?

2./ just how far down the skimmer on my diagram(4ft) is it practical to place the injector pump?......and what capacity pump at different levels would be needed .....and how do you know this....or is this just guesswork?


3./ seeing as most commercial skimmers come in all shapes and sizes....we all know the principles..but JUST what strict criteria are THEY using for THEIR designs? ...or is it all down to their R&D departments and trial and error? ( and waste time/costs and development etc..passed onto us!).

Can anyone tell me what is wrong with my design? and will it work just aswell out of a Square sectioned Acrylic box rather than circular?...if it wont...why?

Once again these questions seem to plague me.....does anyone have any ideas or sound basic principles they can share?

Or Has ANYONE made a large square sectioned skimmer?

who has made the largest skimmer?

Has anyone had any success with bending acrylic sheets at 4ft lengths?

come on guys.................surely your not all rich!...a bit of Diy if done properly can save on the money and end up better.

does anyone have any input on these questions?

 

[DonW]

Collin,
Acrylic is easy to bend. You saw my skimmer. I'm sorry I dont have any particular reason why I made it the way I did. I go out to the shop with a general idea in my gord and come out with stuff. I dont see any reason why your skimmer would'nt work. Possibly a sedra 5K or the OR2700 with needle wheel would be a good choice. At 4 ft I'd go with two pumps and at least a 3/8 venturi. My venturi is also diy. there is a thread on it in the diy section. I'll see if I can find the link.

Don

 

[coolcol]

Cheers Don...yep your skimmer was extremely professional......Thats just the sort of thing i like...somebody to have a go.....

your suggestions are good as was 'Zephrant's'...

Any more brainwaves.....guys

 

[mojoreef]

Hey Collin sorry I didnt see your thread. I have a diy skimmer on this forum to. I designed it orginally to go air stone driven but got caught up in the neddle wheel concept so ended up going that route. Well After putting all the needle wheels on and having it run it was a decent skimmer, but I was disapointed with the amount of bubbles being generated. I left my old system to reduce the electrical cost of a big pump, but with 4 neddle wheels i ended up pretty close anyway.

Long story short I pulled the needle wheels and went back to air drive and a high end stone. Right now I have the air on half strength and I am getting a 4 foot column of shaving cream style foam. To say I am impressed is not enough.

A skimmer is comprised of a few designs. The first if the mixing chamber,this can be a square box, no problem. The finer the bubbles the moresurface area and the more protiens it can hold and lift. The one thing I dont really like about the newer style skimmers is the lack of a neck. Most are only a few inches tall, IMHO this reduces the concentration of the protiens being pulled.

One of the things I did on my skimmer was to build in a wet neck which puts a thin veneer of water down the neck. This allows the foam to rise much facter as the interface bewteen water and foam is slicker then foam against acrylic. Another benefit has been that I have only had to clean it once as the water film doesnt allow skimmer crud to build up on it.


Mike

 

[coolcol]

Hi Mike after seing your Diy skimmer i salute you sir!...it is a seriously well put together design.
It certainly looks better than most commercial efforts i have seen.
It is interesting to note your conclusions on its performance though, and the eventual resumption of the tried and test air stone method.

I had an old sanders internal skimmer years ago and it to was powered with by good old wooden air diffusers...the bubbles were out of this world and apart from he odd occasion when i had to replace the air pump diaphragms and the inevitable wooden diffusers cloging up it performed great..
However i wasnt happy with the diminishing performance and degradation and the limitations using this system.
You need a seriously powerful airpump to use on a 4ft skimmer and am not to sure about the regular maintainance on the air stones/airpump.......do you still use wooden diffusers?

Anyway Your DIY skimmer is an inspiration and an example of what you can acheive with alittle bit of skill and knowledge.
I am looking at a similar needle wheel type bubble generatin system....although i havn't ruled out a simple high quality/low manitainance venturi powered by a good strong pump.

My present (and woefully inadequate!!) Red Se Berlin Skimmer uses such a device......a simple venturi.....
If i could just scale it up (minus the triple bypass) i could have an extremely easy to maintain and affordable skimmer for my 314 gal tank.

Don has also shown that a good skimmer can be designed and made by a competent aquarist to fit his requirements.

Am interested in BIG skimmers....
I like the sound of the wet neck which puts a thin veneer of water down the neck...seems an interesting system!
Anyway If you could have changed anything Mike what would it have been?
Are you happy with your skimmer?

 

[mojoreef]

You need a seriously powerful airpump to use on a 4ft skimmer and am not to sure about the regular maintainance on the air stones/airpump.......do you still use wooden diffusers?

Wrong on both counts my friend. That is exactly what I had thought to. and it was definately the case back in the day. Airation has become a big ticket item here, where many states and orginizations are under taking on reclaiming lakes and rivers,the perfered method is with diffusors and air pumps/ compressors. So the technology has gone up quite a bit. The diaphrams last for at least a year going full steam. The stones are now made of all sorts of different components and can live indefinately if cleaned. The new stones produce finner bubbles then did the wood ones and can be cleaned to new in minutes with a muratic acid wash. The new pumps can be set up far away from the skimmer with the use of air tubeing. My pump is about a 100 feet from the skimmer with no loss of air. Also to keep it from clogging you just put a smaller micron air filter on the air intake tube, that way the small particules just pass throught the stone.

With a smaller skimmer like the one you are envisioning I would say a 1 cfm pump and a single stone, No pump on the skimmer and you could drain straight from the tank itself.

Anyway If you could have changed anything Mike what would it have been?

Well I wouldnt have gone the needle wheel route Colin,lol now I have 4 pumps I need to off load. Other then that a couple thinngs while I was building it, to many screws in the box is one, I should have put another flange where the box meets the tube instead of making the top of the box come off. I might build in a cup cleaner using sprinkler jets.

Other then that I am happy now, its got a 5 foot column of foam rising up, so cant complain

 

[coolcol]

ehmmmm..............very interesting Mike, maybe I will look into this method as an alternative, makes you wonder why so many of the major commercial skimmer manufacturers still favour venturis and/with pinwheels etc .....and lets not forget the new downdraft units.......why dont many provide large 200-600gal dedicated units utilising airstones? .....Any ideas anyone?

I have read a few posts on using airstones.....maybe the technology will make a comeback as the latest ''new'' feature?
If it works and aint broke then dont fix it eh!

Anyway Mike I presume you aware of this alternative before your pinwheel skimmer design why did you not consider it or were you just stuck on using a pinwheel system because you considered it more modern/acceptable in reefkeeping circles.

This is my point that we seemed trapped into blindly accepting the commercial alternatives now pushed at us without fully appreciating the pros and cons.

just out of interest Mike what airpump do you use and what are the new stones you mention/ are they available in the uk?

And what do you lot out there think.....are airstones the way to go?..........should we have left them in the first place in favour of new technologies........
Skimmers i just love them!

 

[NaH2O]

why dont many provide large 200-600gal dedicated units utilising airstones? .....Any ideas anyone?

Perhaps it is a size issue? I am limited on skimmer height for under my stand, and Mike made mention on another thread about neck length. I have no clue about airstone skimmers, but maybe neck length is important. On designing a skimmer for a smaller system, I don't know how big/tall it would have to be. I do understand that some current models are large, I'm just tossing out ideas. I wonder if manufacturers got so stuck on technology when the older style airstones didn't last, but haven't researched new stones. We'll have to see what the longevitiy of Mike's airstones are.

With a smaller skimmer like the one you are envisioning I would say a 1 cfm pump and a single stone

This maybe a dumb question, but wouldn't this be just as efficient as "modern" skimmers? For some reason 1cfm sticks in my head from the skimmer conversation thread.

 

[coolcol]

Interesting point Nikki about size restrictions/constraints.

That would suggest that most skimmers today are in fact fancy comprimise devices to satisfy the strict requirements we expect when building our sumps/ tanks etc.

However the underlying issue surrounding such skimmers would suggest unless we are really constrained by such requirements then it is best to look elsewhere.

I have done a little research after Mikes air stone suggestions and cannot find many skimmers still employing this method of bubble generation, thats not to say there arn't any.
Heres some info from a guy using a 6ft wooden air diffuser skimmer...common sense really but interesting points made.

''''My fellow hobbyist when choosing to buy a protein skimmer don't buy one for aesthetic looks or one that looks futuristic, but an efficient protein skimmer to do the job at hand. Here are some questions you want to ask yourself before you purchase your protein skimmer.

1. Are you getting the maximum traveling/contact time from your bubbles?

2. How long has the protein skimmer been on the market?
(Most protein skimmers come and go very quickly)

3. Is it maintenance friendly?

(If they are a pain in the neck to take apart and clean, then they will get neglected and not function efficiently)

4. Find out how much waste it produces in a 24 hour period.

5. Try and find someone who is using the skimmer of your choice and ask them if they would buy the same skimmer again.

6. If you plan in the future to get a larger aquarium, will the protein skimmer of your choice be able to handle the larger aquarium or will you have to buy a new one?

( think twice, buy once)''''



Or in my case think twice BUILD once!!


Am still not swayed by the use of air stones though!......forget changing wooden ones every month!! what a pain....neglect this duty and the airpumps dont last long as regards the diaphragms...as for the new stones Mike is on about I dont know...most such stones in the past have not been as good as wooden diffussers.....but its been a long time since i looked at the new stones....What ones you using Mike?

There seems a lot of confussion as to what makes a good skimmer, even after all these years we still have threads on this forum comparing different ones to assess their function/efficiency etc. I might add which atracted great interest....nowhere on such a thread was any mention of how they would have compaired before testing...hence the need for the test (very good thread might i add).....but given our knowledge of skimmers today funny how such tests are still needed....dont we have enough insight into skimmer design and performance by now! as well as accurate predictions/assumptions based on simple maths? ...we should have this technology tried tested and sorted by now!

Maybe thats why there are so many different types still out there all trying to temp us with exagerated claims and new fangled ideas 9 some may work.....others....well maybe not!)

All i wanted to know was how far down my 4ft tube could i place a pinwheel pump without loosing the venturi suction?......the further down the better to give the bubbles more contact time.
Am not a mathamatician but there must be a simple set of rules governing the pressures involved....just how much suction is needed to create a venturi at 4ft....-1.5 psi?...-2.3 psi?....maybe its governed by the size and shape of venturi as already propossed!
Maybe someone can conduct a teat to determine some common pinwheel pumps and their actual suction venturi creating abilities?....now i am getting over the top!

Seems I am on my own with this project as there really doesnt seem any sure fire way of determining the multiply factors governing skimmer design.
Seems there is more to the simple principle of Protein skimmers than we care to understand.
Untill there are more tests and scientific analysis of different designs which are undertaken, then we are limited to the rather vague feedback and assumptions based on other aquarists observations (All under different tanks/conditions i might add! not very scientific)

Anyway if anyone is interested here is a site selling big air stone skimmers?

God they look so simple and basic.....but if they work!......but who's going to have a 6ft monster bubbling away (could disguise it as a bubble lamp! lol.)
Back to the Aquamedic 5000 shrty!!

http://www.aquadirect.com/store/customer/product.php?productid=481

Soz for such a long post!

 

[big t]

welcome to the forum coolcol!

It is too bad that you can't seem to find acyrlic tubing over there, that is a drag. If you can find acrylic sheet or 'perspex' as you call it, you can cut it and make a square tube and that will work just about as good as the round tubing. I am not sure how deep you can put the tube and venturi setup but mine is about 10" under water and it has absolutely no difficulty sucking air. My verturi is very simple and works like a champ. I am running the oceanrunner 2700 like Don runs and simply glued a flat disk into the 3/4" fitting that it came with on the intake for the pump. Then I drilled a 3/8" hole in the middle so it effectivly reduced the intake down to 3/8". Between the blocking plate and the actual intake I drilled a 1/4" hole and this is where I inserted my 1/4" air intake tubing. If you do it like this it is simple and effective, and never requires cleaning.

 

[mojoreef]

ehmmmm..............very interesting Mike, maybe I will look into this method as an alternative, makes you wonder why so many of the major commercial skimmer manufacturers still favour venturis and/with pinwheels etc .....and lets not forget the new downdraft units.......why dont many provide large 200-600gal dedicated units utilising airstones? .....Any ideas anyone?

No kiddin. I think its more of a historical thing along with a commercal thing. Air stones were dropped because of maintence, venturis took thier place, then because of maintence again beckets, Downdrafts and so on came into play. Now with the eye on power consumsion needle wheels are at the fore front. That and thier cant be as much money in air pumps and stones compared to todays multi thoughsand dollars skimmers.

Anyway Mike I presume you aware of this alternative before your pinwheel skimmer design why did you not consider it or were you just stuck on using a pinwheel system because you considered it more modern/acceptable in reefkeeping circles.

Actually my friend the unit was orginall designed for the air stone, but I got all caught up in the needle wheel craze thing.

just out of interest Mike what airpump do you use and what are the new stones you mention/ are they available in the uk?

That my friend I cant answer. I got mine from Aquatic Eco systems, they are very big in the commercal area of aquatics. The air pump was a Whitewater and the airstones were custon from Aquatic Eco systems

If it is something that you may want to pursue and I can help let me know.


Mike

 

[mojoreef]

This maybe a dumb question, but wouldn't this be just as efficient as "modern" skimmers? For some reason 1cfm sticks in my head from the skimmer conversation thread.

Yes it was Nikki. The 5000 dollar deltec pushed 1 cfm and so did the 6000 bubble king

Collin you are asking good questions in regards to what makes a skimmer. By no means am I trying to sway you, just giving you another look. I am going by the my tech friend on the lifespan of the stones so that is all I can offer at this point in time.
Here are a few things one must look for.
Small bubbles, the smaller the bubble the more protien it can hold (surface area thing).
A good sized mixing chamber. Can be in a tube or in the box, you want the small bubbles to mix with the water well so you can get the protiens to stick to the bubble.
The more air you put in, the more bubbles, the more bubbles the more protiens you pull out.
Ease of cleaning and maintaining is also a big motive. Look to the wet neck it does work well, Don has tried it on his skimmer to. Its a take off of a Shauran skimmer.

Hope it helps Collin

 

[coolcol]

Yeh that helps me alot you guys.....cheers Mike for the info...will post my pics of my skimmer when i start construction.........thanks all again......lots to think about!

 

[DonW]

I really like Mikes idea of the airstone. I do question wether or not it would work on a skimmer that needs to fit under a stand.
I think we should all put our heads together and come up with a good design, air stone of course. I'll build it and test it as long as the cost is reasonable.

Don

 

[Zephrant]

Well I’m both a manufacturer and a long time hobbyist, so I'll throw in my two cents.

Tubes are used partly for looks, but mostly for manufacturing ease. It takes more time to build a four sided box, flush trim the edges, round them over, then flame polish them, than it takes to cut a tube, and glue it on.
I can counter-sink the tube in to the flanges, and get a very strong joint. This is harder to do with a square box.
Tubes are stronger than boxes- You can use thinner material, and still be stout.

On #2, I can't tell you for sure- Built a test setup in a bucket, and do some testing. It is a curve- The deeper you go, the less air. How much air do you want? Get an Air flow meter and a ruler, and make yourself a graph.

On #3- Some are flat out copies of other designs, but most of us build and test the new designs on our own tanks, and then locally with a few customers that get the "prototype" units for a discount, then release the design on the public. Building your first skimmer from scratch is hard to get right. After you have done some you learn what works/fails, and you refine the design.

I've not seen a very big square skimmer. KR2 makes very big round ones.

While acrylic is "easy" to bend, it is very tough to do it well- Bending a tube out of a big sheet is a pretty serious job, and seaming it well is also tough. Not impossible for a DIY guru, but it would take a lot of effort.

Mike- Can you explain this a little more?

The one thing I dont really like about the newer style skimmers is the lack of a neck. Most are only a few inches tall, IMHO this reduces the concentration of the protiens being pulled.

In my experience the purpose of the neck is to merely provide a smaller cross section such that the air being injected to the skimmer is sufficient to lift the foam out of the neck. I've not noticed any effect on the concentration of the protiens. I keep the necks relatively short on my designs because it allows the main chamber to be taller, for the same maximum height.

The air stone idea is very interesting- Throw us some more pictures of your unit now Mike!

Nikki- I suspect Mike was agreeing with your second question, not the first. It was a very valid question. My own testing shows that the Beckett will pull about 1CFM as well, at 550 GPH.


Zeph

 

[coolcol]

Great idea Don....lets get the ball rolling!
And Zeph...you have just explained so much in that last post of yours it really is all starting to make sense....the bit about the neck is well explained.....that does seem to be the main reason for restricting its diameter ....to allow the air pressure in the skimmer to push the foam out.....i have seen a few DIY ones with necks about 1in !!!! the foam must fly out!!

I have looked at shaping and forming acrylic...you need an oven to soften it the form it over a tube if you want a tube that is....preety hard to form a 4ft long piece so i guess am stuck with a box.....still it should look ok with the solvent leaving almost clear joins and all the posh pipe bits and pieces....but will it work?

Always wondered why manufacturers used round tube skimmer construction...now i know!!

Thanks again Zeph.....nice one.

Next step........airstone skimmer comparisons.!!!

 

[mojoreef]

Great Post Brent!!

In my experience the purpose of the neck is to merely provide a smaller cross section such that the air being injected to the skimmer is sufficient to lift the foam out of the neck. I've not noticed any effect on the concentration of the protiens. I keep the necks relatively short on my designs because it allows the main chamber to be taller, for the same maximum height.

Brent I am recalling old memories so bare with me. With a longer neck it allows for more of the water to drain off the bubbles leaving more protien on the surface of the bubbles. Thus a more concentrated skimmate. With the shorter neck you end up getting more water in the cup or folks turn it down and get a very dry foam.
As a Manufacturer of skimmers Brent you are in a different situation. Most folks have to put skimmers under their tanks or close by and dont have the room for a long necked skimmer. The box is the mixing chamber, think of the neck as the concentrator?? that make sence, lol


Mike

 

[coolcol]

Thats another good point Mike.....i think in essence the longer the neck the more dry the skimmate.......so the narrow neck pushes it out like Zeph stated...and up to a point the longer this neck gives the water more time to drain off thus concentrating the skimmate....yes i agree with that Mike....excellent!!

What would you assume the most effiecient neck height to be in this regard Mike?

I assume at a point the bubbles would become too dry and fall back into the main chamber.....until eventually the top layer of the protein skimmer would resemble the collection cup!!

This is very interesting....Mike thanks for this info, I am learning new stuff every post here!

I wonder.......... a simple test on any skimmer to lengthen its neck then record the results of the skimer concentrate would be quite advantageous in designing a new skimmer.
Practical restrictions taken into consideration i would imagine you could taper the neck to a very small top say 1/2in and over 1foot long!....all this for a 10in skimmer diameter....ehmmmm, make me want to be a skimmer scientist just thinking of the possibilities. :lol: