Beckett vs. Needlewheel skimmers
- Thread starter alwest45
- Start date
sherm71tank
Premium Member
:crazy1: :eek2:Joking?
hahnmeister
In Memoriam
You cant place a venturi (beckett, downdraft, mazzei, injector, etc) after a NW. The back-pressure on the NW will prevent it from sucking in air. To run becketts on the intake of a NW would restrict the intake. No, you cant combine the two, nor would you want to.
Roland Jacques
Premium Member
<a href=showthread.php?s=&postid=8404506#post8404506 target=_blank>Originally posted</a> by sherm71tank
Joking?
bernie lyons
New member
needlewheel /beckett
needlewheel /beckett
well . why not bring back the asperator skimmer designs back ..klaes . The advantage of these skimmers is that they use
a substantial pump with a chopper impeller to produce fine air into the water . These designs do not suffer from a silly snaIl getting caught in between the pins of a pinwheel and causing an "unbalanced" spinning action which ultimately destroys the magnet assembly on the pinwheel itself .
MTC produced such a unit years ago and it worked incredibly well !
Cost is a factor however and hopefully a company today could
produce these at a more reasonable price.
Just a thought .
bernie
needlewheel /beckett
well . why not bring back the asperator skimmer designs back ..klaes . The advantage of these skimmers is that they use
a substantial pump with a chopper impeller to produce fine air into the water . These designs do not suffer from a silly snaIl getting caught in between the pins of a pinwheel and causing an "unbalanced" spinning action which ultimately destroys the magnet assembly on the pinwheel itself .
MTC produced such a unit years ago and it worked incredibly well !
Cost is a factor however and hopefully a company today could
produce these at a more reasonable price.
Just a thought .
bernie
sherm71tank
Premium Member
Got a pic or linky?
Waylander
New member
I'm a geek. I just had to try it....
http://reefcentral.com/forums/showthread.php?s=&threadid=958085
http://reefcentral.com/forums/showthread.php?s=&threadid=958085
kimoyo
Active member
Sherm71tank - have you measured the pump with a watt meter or is 125W just the pumps rating?
Zephrant - Would a beckett with wider but shorter cylinders perform worse than a taller thinner one?
Have you thought about increasing the air tubing to 3/8 (or more) so you can run a lower wattage pump and still get 45 scfh?
On your chart why do you have the beckett 2' above the water level? Does the performance (bubble size or air draw) increase as the beckett injecters go higher above the water level? I thought water level was the same. Thanks.
Zephrant - Would a beckett with wider but shorter cylinders perform worse than a taller thinner one?
Have you thought about increasing the air tubing to 3/8 (or more) so you can run a lower wattage pump and still get 45 scfh?
On your chart why do you have the beckett 2' above the water level? Does the performance (bubble size or air draw) increase as the beckett injecters go higher above the water level? I thought water level was the same. Thanks.
sherm71tank
Premium Member
Just what the pump lists as its wattage.
kimoyo
Active member
Then its running a lower wattage than that
. My pump dropped around 85w running dual becketts, you really should check. If your using 125w for 100scfh your getting better watts/scfh than BK's or the dart needlewheel. But your probably using less than 125W if thats just the listed wattage.Have you tested non-recirculating also?
hahnmeister
In Memoriam
"Would a beckett with wider but shorter cylinders perform worse than a taller thinner one?"
I know this one. You have two variables here to consider. Tube diameter, and height. The height is going to vary the injector's relative height in comparison to the water level in the skimmer's main reaction chamber. So the lower it is, the more head presure it will have to deal with. Imagine trying to blow bubbles into a body of water at 6" of depth, and then at 3' of depth... the 3' would be much harder, no?
The tube diameter that the beckett's output must travel determines the pressure as well. If you go too small, you can create a back pressure on the injector itself, and you lose air intake, but if you go too small, the mixture can hang travel too slow in the pipe on its way down, and smaller bubbles can end up combining, and larger bubbles can end up rising inside the chamber... creating pockets of air that disript the throughput until the back-pressure on the injector causes it to lose its air intake. See, according to Newton's conservation of energy laws, as the pipe diameter decreases, the speed increases. As the speed increases, the pressure also drops.... this is the fundamental law that gives us bernoulli equasions and explains how venturis work. Anyways, the smaller pipe keeps the water flowing faster, and prevents it from regaining pressure until its inside the skimmer. If the pipes are too big, pressure increases, and we all know what happens to air bubbles when pressure increases (and its in a mix with something more dense like water)... it wants to rise with more and more bouyant force.
So the final response to your question is 'depends'... as Zephrant pointed out, there are no linear interpolations to be understood here... every variable is on a curve, and every ideal is relative. There are 'sweet-spots' for every design depending on the other design parameters.
I know this one. You have two variables here to consider. Tube diameter, and height. The height is going to vary the injector's relative height in comparison to the water level in the skimmer's main reaction chamber. So the lower it is, the more head presure it will have to deal with. Imagine trying to blow bubbles into a body of water at 6" of depth, and then at 3' of depth... the 3' would be much harder, no?
The tube diameter that the beckett's output must travel determines the pressure as well. If you go too small, you can create a back pressure on the injector itself, and you lose air intake, but if you go too small, the mixture can hang travel too slow in the pipe on its way down, and smaller bubbles can end up combining, and larger bubbles can end up rising inside the chamber... creating pockets of air that disript the throughput until the back-pressure on the injector causes it to lose its air intake. See, according to Newton's conservation of energy laws, as the pipe diameter decreases, the speed increases. As the speed increases, the pressure also drops.... this is the fundamental law that gives us bernoulli equasions and explains how venturis work. Anyways, the smaller pipe keeps the water flowing faster, and prevents it from regaining pressure until its inside the skimmer. If the pipes are too big, pressure increases, and we all know what happens to air bubbles when pressure increases (and its in a mix with something more dense like water)... it wants to rise with more and more bouyant force.
So the final response to your question is 'depends'... as Zephrant pointed out, there are no linear interpolations to be understood here... every variable is on a curve, and every ideal is relative. There are 'sweet-spots' for every design depending on the other design parameters.
sherm71tank
Premium Member
<a href=showthread.php?s=&postid=8415867#post8415867 target=_blank>Originally posted</a> by kimoyo
Then its running a lower wattage than that
Have you tested non-recirculating also?
Yeah, I know the pumps draw less than stated in most circumstances. I made only non-recirc for years. The recirc is much more stable and I can run much higher air volume through it than a non recirc beckett. I should get a killawatt for fun.
Zephrant
Premium Member
I agree with Hahn- Wider gives you a slower water movement, and a shorter path for the air to make it though the water. Tall and skinny gives faster water flow, but a longer path for the air. Within reason, they both work well.
As I mentioned earlier, I run 1/4" line on purpose- Stock Becketts need the air restricted somewhat to make small enough bubbles. I chose to do that with 1/4" valves and plumbing, but you could certainly run 3/8" tube/valves and then turn them down some.
If all you want is massive air numbers, take the valve/tube off completely and drill some 1" holes in the side of the Beckett chamber.
In the chart the Beckett was held 2' above the water level because I had to cascade the water in to a bucket to measure the GPH.
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