Skimming Principles

[tinygiants]

I added it to the calc sheet. I also added into the water dwell calc to take air volume into count.

[crazzyreefer]

Cool, it seemed right to me, but I didnt have all the facts...

when you get a chance post a drawing.....

[tinygiants]

Playing in excell is one thing, but CAD... I will try. The basic design is going to be the standard countercurrent skimmer (6") as shown on snailman's site. In order to get my bubble dwell time, I am adding a 3 gpm recirc. The goal is to draw this water from below the bubble cloud. This will allow me to create the current to keep the bubble in suspension. For adjustability sake, I will try to make my recirc rate adjustable. This will make for quick bubble dwell adjustments.
Dale

[tinygiants]

Crazzyreefer

Where did the 1.17 inch/second come from for bubble rise. 3cm/s equates to 1.181 inch/second. I read the bubble pdf file you posted, but it was way over my head.

With our small bubbles, does Stokes Law govern the movement?

[crazzyreefer]

1 centimeter = 0.393700787 inches X 3cm = 1.811023610
1 centimeter = 0.393700787 inches X 2cm = 0.787401574
1 centimeter = 0.393700787 inches X 1cm = 0.393700787

a program must have altered the value.. and I never rechecked it....thank you...

[tinygiants]

The difference only equated to 2 seconds in my calcs. In truth these calcs assume a constant, but as the bubble gets loaded the rate will change. Is that change linear? Can it be described in terms of a formula?

I am thinking that maybe for the sake of modeling I should use 2.5 cm/s as an average. Any ideas on that.

[crazzyreefer]

no it more to do with the types of organics and the load rate, not as simple as that. but at least the paper I found only found 1cm difference in travel due to load. a gate valve on the pump will be able to fine tune the treadmill effect.

[duhfactor]

Tinygiants,
Are you thinking of plumbing a simple pvc pipe from the reaction chamber under the bubble cloud, through a pump, and back up to the top of the reactor? I'm wondering if there would be any value in running that pipe diameter a bit on the larger side so that the pressure coming out of it's upper orifice is low. It seems to me that higher pressure has the potential to strip proteins from the bubbles in that area of the skimmer which is probably going to be the most productive for bonding. It's not a design killer, just a thought.......


Damon

[tinygiants]

I agree. I am planning on a 1" pipe for mine. I only need 2 - 3 gpm. I want it to enter through multiple 1" T's so as to keep turbulence down.

[duhfactor]

Sounds good, I'd love to see it.

[tinygiants]

I am getting the pipe today.

[tinygiants]

Ii got the pipe, now I need to special ordere a few fittings. I will catalog them and get the order in tonight.

[duhfactor]

Tinygiants,
If it's not too much trouble, it would be great to have you post the parts you catalog, in the event we can reproduce your design. Have you decided on your pumps yet? Do you have a digital camera to post pics?

D

[tinygiants]

I do have a camera. I will update. To be honest though, the snailman design for air stone skimmers is right on for my application. The only change I will make is the addition of the recirc line (if flow rate testing shows it to be effective).

Dale

[duhfactor]

Dale,
How tall are you planning to make it?

[tinygiants]

Main chamber is shaping up to be 60". I will have to play with the bubble neck and see what it takes to get foam to the cup.

Dale

[crazzyreefer]

dale dont forget to minus the wall size of the pipe, it might make a differance, or it might be that im anal..I remade my calculator, it will take a few days to be able to use it, it works a lot better thanks to your help... although it worked it converted numbers up..down and into incompatible units many more times than what was needed.. good luck on the skimmer

Nicholas

[tinygiants]

You were right, the pipe is not 6" on the inside. Mine is 5 3/4". So it affected my numbers a little.

[tinygiants]

I have all of my special order stuff on the way. I will need a hand full of 1" and 1/2" PVC stuff, but I can get that local. I am hopeful to get started this weekend.

[tinygiants]

I just ordered the air flowmeter and the water flowmeter. I should be able to get pretty good info on what is happening inside the skimmer.

[crazzyreefer]

do you have a link?

[tinygiants]

Air Flow Meter

Water Flow Meter

I have a bid on one more water meter. It is a higher grade meter, but I have to wait a few days to see if I win.

I want a meter on the recirc and the feed.

Dale

[duhfactor]

Dale,
Using flow meters is a great idea. Are you using PVC or schedule 40 piping, or acrylic tubing? I was just wondering if you will be able to see inside the skimmer to view it's operation? I don't think it's critical, just curious.

Damon

[tinygiants]

I am using all PVC Pipe. I can not afford to do this in acrylic. I will be able to remove the top to watch the bubble chamber from above, and I may experment with the window that MarkS put in his skimmer. Time will tell.

[duhfactor]

I haven't read that thread, do you have a link? I have bought acrylic pipe from US Plastics in one foot lengths. Here is a link.

http://www.usplastic.com/catalog/pro...uct%5Fid=11248

Looks like $9.52 for a foot of your needed size. They'll cut it for you to whatever length you want at no charge. Would there be any advantage to using two slip slip couplings and put a foot of the acrylic tube in the middle of the main chamber someplace? I've drilled and tapped their acrylic for screw in fittings without any trouble (not that you would need to, unless it just happened to be in the place you wanted to bring water in or something). (That would be my luck )

lookin' good,

Damon