Skimming Principles

problem is the needle wheels recirculate the water/air mixture, which strips the organics.

on a different note can a air molecule attract a phoshore molecule or a nitrate molecule, I was reading that in waste management this is one of the primary ways of stripping phosphates out of waste water prior to reuse. ChemE?
 
Wastewater isn't my forte, but I'll do some checking.

The bathroom scale idea is workable in theory but I doubt very very much that a bathroom scale is anywhere near precise enough to measure a few grams difference on something that weights 30-40 lbs. Sorry to rain on the parade. An optical sensor that measures water/foam interface height might be a better method.
 
ever thought of batch processing the water? I.E. every 2 minutes pump the skimmers volume in water into the skimmer and leave it to react for 2 minutes.
 
Well I got sick and tired of a messy worksheet. So I made Version 3.

This version will calculate the air volume required to meet the 13% Saturation.
It does all of the messy conversions on the fly (cubic inches - gallons, GPH - GPM, and so on).
It calculates water dwell time taking into consideration the volume of air in the skimmer.
Bubble dwell is calculated for a counter current skimmer.
For those that employ a recirc pump on the skimmer body, it calculates the recirc effect on the bubble and associated times.

While calculating this I found it interesting that the airpump does not need to be a brute if you keep the bubble suspended in the water column.

Let me know if you find any errors in my calculations.

Dale
 

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recirculation rate isn't correct, the common misconception including escobal, is that the water recirculating isn't stripping the organics that hold the bubble stable, so where you have 3min its 70 sec this is the biggest problem with the skimmers that are on the market, except maybe RK2, but its because of lack of proper insight, and or the limitations of cabinet height/mass marketing that forces them to build a poor product. bulk batching wouldn't work, due to stripping. look at wet drys systems, I was on the leading edge 20 years ago designing them, there was a couple in the mid west, and a Swiss group, and even though I had a hand in the design I realize it was poor design, but it still sells today. another problem you have is your 3 inch tube, go larger, you are creating a lot of turbulence with 3 inches, again stripping... but hay this calc is easier to read...
 
ChemE said:
Wastewater isn't my forte, but I'll do some checking.
Click to expand...

There are some good links in this thread, for wastewater processes, and associated bacterial phosphate processing studies. One of the last links describes a new single vessel Aerobic to Anaerobic and back cycle that is much simpler than current technology.

Most experts believe that Nitrate and dissolved Phosphate processing can only be accomplished by the Aerobic to Anaerobic process.

http://reefcentral.com/forums/showthread.php?threadid=671936&goto=newpost

I hope the links are helpful.

Happy Reef Keeping > barryhc :)
 
I dont trust optical sensors in a skimmer due to all the organics, no a bathroom scale wouldnt work well for a small skimmer, but I have many scales here that are fine tuned and measure ounces from 50 lbls, but most larger skimmers have 20-30 lbs differances so on that part a scale that measured every 1-2 lb would work.
 
heterotrophic active biomass removes the phosphates, the higher the concentration of liquor, (organic solids) the higher the rate of Phosphate removal.
 
crazzyreefer said:
recirculation rate isn't correct, the common misconception including escobal, is that the water recirculating isn't stripping the organics that hold the bubble stable, so where you have 3min its 70 sec this is the biggest problem with the skimmers that are on the market, except maybe RK2, but its because of lack of proper insight, and or the limitations of cabinet height/mass marketing that forces them to build a poor product. bulk batching wouldn't work, due to stripping. look at wet drys systems, I was on the leading edge 20 years ago designing them, there was a couple in the mid west, and a Swiss group, and even though I had a hand in the design I realize it was poor design, but it still sells today. another problem you have is your 3 inch tube, go larger, you are creating a lot of turbulence with 3 inches, again stripping... but hay this calc is easier to read...
Click to expand...

Ok - I think you are misunderstanding the design plan I based this on.

The recirc rate will be seperate from the feed. It is measured in GPM, not seconds. In order to achieve enough water velocity to slow the bubble down I had to add it. If I just speed up the feed rate, I sacrifice the water dwell time (while the bubble dwell would be ok). The water being recirced will be collected from the same area as the skimmer overflow outlet. Very few bubbles should be pulled through the recirc line.

The water dwell calculation is based on feed rate only. It does not include the recirc.

The water velocity calc adds the feed rate and the recirc rate for combined feed rate to use in the calc.

Does that answer the concern? Or do I still have a error.

Dale
 
This makes more sense to me. I looked through your calculation spreadsheet tinygiants, and it seems to work. I'm going to hold off of the inclined skimmer design for now, I like where this is going.....

:bigeyes:

D
 
nope thats the same as that convection type.. makes sence, one number that isnt in your cals is bubble rise it needs to be between .40 and 1.17 if you got this...you got it...other wise it will be sucked like a vaccume when the organics attach. was 60 inches just your liquid chamber part, how long of a foam area? you have the design right! see,,,,now... this is where the manufatures do not even start to make it work correctly.... way to go!
 
Question, what is the phosphate and nitrate levels of the skimmer effluent, if its off the chart, use rodi water to dilute by 10X and please post your results, this will give to different answers, either its not removing them, or they are being neutralized as the waste management seems to express.
 
60 inches is the liquid chamber.

Why does the bubble rise rate need to be between .40 and 1.17? As long as the rise rate is greater than the water velocity, the bubble will maintain positve boyancy. The bubble will not achieve maximum organic bonding till it is reaching the top of the water column anyway.

I am planning to buy a 6" PVC Pipe and either a 4" or 3" foam riser pipe. I was going to experiment with the foam pipe length as well as maybe a wetneck.
 
since we are removing multiple types of organics, not all bond at the same time, same way, and affect bubble dwell differently, Maybe I'm wrong... this part isn't proven, nor suddied in depth. but if you can keep you numbers in this range you wont have a potential issue. so what is your bubble rise?
 
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
 
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?
 
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...
 
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