Optimized Beckett
 

Like everyone, I have been following the beckett vs needlewheel debate. I have beckett skimmers and have played with needlewheels but kept coming back to the becketts. Needlewheels have improved at the point of air/water mix - better needlewheels. I started wondering what could be done at the air/water point of becketts. Simple and obvious as it turns out.
The trend has been to go to larger and larger pumps to , basically, force water through faster so that it 'tears' smaller bits of air off of 4 large air inlets. I sealed the 4 large inlets and used a 1/16 bit to drill 24 smaller holes around the beckett (2 rows at the same level as original holes). It seemed logical that moving water would tear smaller bits of air off of 24 smaller inlets than 4 large air inlets. The logic is correct.
I have a DIY 10" diameter, 32" high beckett that I was driving with a mag 18. With the modified beckett, it did not matter to bubble size if I ran it with the air restricted or wide open. Of course, with unrestricted air, bubbles flooded the sump. I was getting enough air that I had to restrict it AND lower the water level in the skimmer to keep from flooding the cup. Out of curiousity, I tried a mag12 and had the same results. Basically, it becomes a matter of how much air do you want - at much lower velocity (read turbulence inside the skimmer). I don't have anything smaller but as soon as I can find a lower flow pump, I expect the resuts will be the same. I'll have to play with it this weekend to verify it but this might remove the complaint that becketts have to have such serious pumps to work efficiently.
With the size and number of holes that I used - on the mag 18 and mag 12 - it looked like whipped cream. Both pumps could fill the skimmer and start flooding the sump It will be interesting to try smaller pumps. There are several things that I would (and will probably get around to trying - sometime) like to try like varying hole size and number of holes. I definitely won't need more air but it would be interesting to see if one could use more and smaller holes, perhaps with an air pump, and really get into some large scale applications.

What do you think?

I think I would like to try it myself. It seems to me though you have restricted the air flow by having the numerous small holes. Can't you do the same thing by just restricting the air valve on a non-modded beckett? Oh, and it doesn't make you a geek. It makes you cool!

I ran it unrestricted. Made a mess, too. :)

I think what will be interesting is that (I think) it can be done at much, much lower velocity/volume/pressure than has previously been done.

Hmm... I just took the beckett out to try a mod I did on my RPS2000 skimmer. Well, I have glue to seal the large beckett holes and plenty of drill bits handy. Looks like I have a weekend project! ;)

Standard becketts rely on air restriction to control bubble size - too much air and if throws large bubbles. The bubble size did not change even wide open. I could draw way,way more air than the skimmer could handle but I could not make it draw large bubbles. I am I saying that in an undestandable way?

I'm picking up what you're putting down. I just don't understand the physics of it. Seems like restricting the air would accomplish the same end result (though it would be great if I were wrong!).

I wish you guys posted pics of this stuff. I have no idea what you are talking about!

Hey Jonathon, don't worry. I'll show you all about it! BTW, I'de love to let you borrow the recirc beckett for a weekend to see how it compares to your monster skimmer. Oh yeah, and Snow Cap seasonal is out now. :beer:

Fun, fun, fun. Needs pics, pics, pics. I guess I need to buy a spare beckett to play with.

Snoooooow Cap......mmmmmmmm<slurp>

I'll try to get some pictures this weekend. Not much to it, though. 5 minute mod to plug 4 holes and drill 20 - 30 small holes to replace the ones you plugged.

Can you get some pics of the foam, to show the difference? How's the mod working so far?

I DEFINITELY want to see pics of this beckett! I have two extra becketts as spares, so this would be an interesting experiment.

What size drill bit did you use and where did you drill the holes?

I used a 1/16 drill bit for the new holes.

It is very, very noticeable. I could always restrict the old becket to turn the upper column to 'milk'. With the modded beckett, I can actually move the bubble line down the skimmer even to the point of flooding the sump with bubbles as the entire volume of the skimmer 'milked out'. It was getting enough air that I had to drop the water level 4" from where it was set with a non-modded becket.

I'll be modding skimmers that I have built for friends over the years this weekend but I will try to remember the camera and get some pics as I do one of them.

Would a beckett half the size of a normal beckett make any kind of a difference?

There would be a scalability factor but I don't know what it would be. Modded this way, it is going to take less pump and then if it is scaled down?????
Do you have a way to scale a beckett down? It should not be that hard to makes something small but functional. Perhaps a standard venturi with even smaller multiple holes?

Have you tried this with a pressure rated pump? I have an Iwaki 55RLT on my MR-2, how do you think it will react?

I could see how it would work.

After building my own 5ft beckett monster I've just not got enough air flow. I've been running the beckett fully open while I look for a bigger pump.

But its been bugging me why everyone is having to restrict air flow to get smaller bubbles.

Now that I look at my beckett you are right...those holes are huge. So that by slowing the air flow (restricting) less air is available and the resulting bubble after it goes through the hole is smaller.
This would also rob energy from the beckett flow because it is pulling against a vaccum. (technically the beckett creates a low pressure and because of restriction has a lower pressure outside the housing) Which is not the operating enviroment that a becket was designed for .


I think what you've acomplished is akin to using a finer air stone and now the bubbles are mechanically formed smaller by using smaller holes. This would then allow you to go fully open on the air. With enough small holes you may have more air available than with those 4 holes. (I wonder whether the flow becomes less or more turbulent when it goes around the ball of the becket.)

thats my theory.( Its been a while since I did fluid mechanics)

I just finished pluging my spare beckett with epoxy.

"Have you tried this with a pressure rated pump? I have an Iwaki 55RLT on my MR-2, how do you think it will react?"

Just the Mag12 and Mag18 so far. The 55rlt will eat either pump that I have tried on driving an unmodded beckett. I see no reason for that to change on a modded beckett. However, the improvement on the mag18 was enough that I might put it up against your 55 on an unmodded beckett.:D I was totally filling the skimmer (24" of 10" body with 8" of 3 1/2" neck) and backfilling to the sump. I just don't have the 'numbers' to quantify this but I think this may actually put people to looking for smaller pumps for the beckett.

rivan,
Exactly! Thank you! You state it more clearly than me.

I'm using a blueline 1100 pump with my beckett at 5 ft. Still pretty impressive air flow compared to a venturi but my skimmer has much more capacilty. I've got to borrow something bigger before I buy. But when you start looking at 200Watt pumps I think its better to build a less tall skimmer.

tTere's a Barr (john?) guy who builds skimmers and frequenly posts diy here. He's got a diagram that shows airflow on a becket is non-linear. So that the bigger the pump you get even more air than expected. It looks like for his 4ft beckett skimmers he recomends a pump which does 800gal/hr at 12 ft. Most pumps die at 12 ft head.
He would also be the best i think at testing you're mod and putting some numbers on it.

Waylander,
What did you plug the holes with? Epoxy?

rivan,
Its Brent Barr of Barr Aquatics, Zephrant here on RC, and a sharp cookie if there ever was one.

where's a good place to get the beckett. I got one from lowes b4 but I don't see them now.

Gotta try this!

H20ENG - I plugged the first few with som acrylic rod and weldon. Since then I switched to epoxy.