Skimming Principles
- Thread starter tinygiants
- Start date
tinygiants
New member
Nice looking skimmer.
I do not like how my skimmer is handling the foam export.
I do not like how my skimmer is handling the foam export.
BeanAnimal
Premium Member
Doh... more details?
crazzyreefer
New member
the organics creats surfactants on the extrior walls of the bubbles as they form, after 120 seconds the exterior walls have fully formed and increasingly collecting more organics and trace elements, Ill find the page that was linkd I believe to this thread or one of the other threads on this matter, it showed proof of what is being removed from our tanks, both in skimmate and in sludge from the riser tube, the riser tube had had larger percentage of heavy metals. a proper bubble would be less likly to burst and more likly to cary these metals into the skimmate instead of depositing them on the riser tube.
found the page...
http://reefkeeping.com/issues/2002-12/rs/feature/index.php
As for buble rise rate this is where I found the info
this comes from the UCLA Paper on buble rise
Bubbles are ellipsoidal in shape, motion is irregular, and velocity is independent of
bubble diameter (approx. 28 - 30 cm/sec) for bubbles having radii up to 0.75 cm. For
larger bubbles their velocity tends to increase to 35 - 40 cm/sec, but they are not stable
and tend to subdivide into smaller bubbles.
Now we know we are having diffrent numbers comming in, one person reported 5 inches per second and I think your is 8 inches per second, these are way off, we will have to find away to explain the diffrences and then work togeather on a soulution.
jnarowe, I submitted your reply to the mods for review.
found the page...
http://reefkeeping.com/issues/2002-12/rs/feature/index.php
As for buble rise rate this is where I found the info
this comes from the UCLA Paper on buble rise
Bubbles are ellipsoidal in shape, motion is irregular, and velocity is independent of
bubble diameter (approx. 28 - 30 cm/sec) for bubbles having radii up to 0.75 cm. For
larger bubbles their velocity tends to increase to 35 - 40 cm/sec, but they are not stable
and tend to subdivide into smaller bubbles.
Now we know we are having diffrent numbers comming in, one person reported 5 inches per second and I think your is 8 inches per second, these are way off, we will have to find away to explain the diffrences and then work togeather on a soulution.
jnarowe, I submitted your reply to the mods for review.
crazzyreefer
New member
tiny, yea I lost a decimal some how the proper rise rate would be 28cm-30cm or 11.02-11.81 inches per second to reach the correct rise in static water is 118 feet worth of pipe, or a counter curent model to substanualy slow down the bubble rise
tinygiants
New member
Well, I got some info from Spazz on his NW. I will crunch the numbers and see how my bubbles compare to his.
Dale
Dale
BeanAnimal
Premium Member
How is the skimmer working?
Are you using the recirc?
Are you using the recirc?
tinygiants
New member
I am still not happy with my tunning. I either flood or get nothing. I am trying to find the sweet spot.
Right now I have the recirc off while I base line.
Dale
Right now I have the recirc off while I base line.
Dale
BeanAnimal
Premium Member
What do you feel is making the adjustment so hard to increment? Do you see a particular design flaw or weak point aht is causing the all or nothing?
tinygiants
New member
I am thinking that my riser is to tall. I may need to raise my water level higher than my hartford loop is plumbed for in order to compensate. I can remove a pipe and add a longer one, but it will have to wait for the weekend. If I use the air to compensate, I get skimmate. I just get more than I am thinking I should. I get 3 cups of gingerale looking stuff. I am after coffee.
I may try a quick test install of my cup right off the 4" fernco. That will lower my cup by about 8". Then I can see the difference without total commitment.
Dale
I may try a quick test install of my cup right off the 4" fernco. That will lower my cup by about 8". Then I can see the difference without total commitment.
Dale
What's the problem with using the recirculation pump to just deliver more water from the sump? Same flow into the skimmer top... you're just delivering more water from the rest of the tank as opposed to from the bottom of the skimmer. Maybe I'm just zoked right now, but I can't figure out/remember why you did that....
Do we have any more solid data on the bubble size or bubble size distribution from high-end water pump driven skimmers? Apart from the theoretical questions so far, it would be good to compare your bubble sizes/rise rates to more examples of other skimmers.
G1
Do we have any more solid data on the bubble size or bubble size distribution from high-end water pump driven skimmers? Apart from the theoretical questions so far, it would be good to compare your bubble sizes/rise rates to more examples of other skimmers.
G1
tinygiants
New member
I am calculating Spazz's bubbles right now.
I fed from the bottom to improve current while keeping a good dwell time.
Dale
I fed from the bottom to improve current while keeping a good dwell time.
Dale
BeanAnimal
Premium Member
goby the difference is simple.
Extra water from the sump is "new" water, or the same as increasing the turnover rate of the skimmer.
Pump water out of the skimmer bottom back into the skimmer top (or vice versa), allows the same water to continue to be skimmed and make contact with the air.
It is the same as using a pump to mix your coolaid, or using the pump to pump new water into your container (displacing the coolaid that is already there).
Bean
Extra water from the sump is "new" water, or the same as increasing the turnover rate of the skimmer.
Pump water out of the skimmer bottom back into the skimmer top (or vice versa), allows the same water to continue to be skimmed and make contact with the air.
It is the same as using a pump to mix your coolaid, or using the pump to pump new water into your container (displacing the coolaid that is already there).
Bean
If the contaminates you are trying to remove are generally spread in all of the systems water, where the return water comes from makes little difference. In fact "new" water would be higher in concentration than recirculated water, so it would skim more efficently. Your analogy about coolaid is incorrect in that all of the water in the system is already coolaid.
You can skim the tank a few gallons at a time or move the whole tank through it and it won't effect the skimmer efficiency negatively.
BeanAnimal
Premium Member
Sam that could not be further from the truth.
1.) Recirculating water that is already in the skimmer and in contact with air will presumably help remove some of the more stubborn protiens.
2.) If your logic were to hold true, then the flow rate through the skimmer is irrelevant over a long period of time (say 2 days).
3.) How do you figure that "the more protien rich water" would skim more efficiently? More efficiently as compared to what? The same skimmer with a higher flow? A bigger skimmer with a smaller flow? This statement directly contradicts your premise that it does not matter where the water comes from.
4.) All of the water in the system is NOT cooliad. The water that has been agitated with air is more apt to release it's protien. (see point 1). This is why surface skimmed water has more protien that that of water that comes from even a 1/2 of water. (read Shimek's, Escobal's, Calfo's, or anybody elses studies and observations regarding this fact).
5.) Cleaning the water until it is 50% clean and returning it to the tank twice is more efficient than cleaning the water 25% and returning it to the tank 4 times. The same itterations can be used to show the dilution of 5 gallon water changes vs 10 gallon water changes. The terms in use of electricity will follow the same pattern.
You can skim the tank a few gallons at a time or move the whole tank through it and it won't effect the skimmer efficiency negatively
This makes utterly no sense and is actually 100% wrong. You need to look up the word efficiency and also have a look at the principle behind skimming (foam fractition). I highly recomend Esobal's book as a starting point. I also recomend a hard look at linear overflow lengths and how they relate to the ammount of protiens that end up in the water going to the sump. You will also find a lot of information in the wastewater industry that uses these same principles (this is us reefers stole the technology from).
Bean
1.) Recirculating water that is already in the skimmer and in contact with air will presumably help remove some of the more stubborn protiens.
2.) If your logic were to hold true, then the flow rate through the skimmer is irrelevant over a long period of time (say 2 days).
3.) How do you figure that "the more protien rich water" would skim more efficiently? More efficiently as compared to what? The same skimmer with a higher flow? A bigger skimmer with a smaller flow? This statement directly contradicts your premise that it does not matter where the water comes from.
4.) All of the water in the system is NOT cooliad. The water that has been agitated with air is more apt to release it's protien. (see point 1). This is why surface skimmed water has more protien that that of water that comes from even a 1/2 of water. (read Shimek's, Escobal's, Calfo's, or anybody elses studies and observations regarding this fact).
5.) Cleaning the water until it is 50% clean and returning it to the tank twice is more efficient than cleaning the water 25% and returning it to the tank 4 times. The same itterations can be used to show the dilution of 5 gallon water changes vs 10 gallon water changes. The terms in use of electricity will follow the same pattern.
You can skim the tank a few gallons at a time or move the whole tank through it and it won't effect the skimmer efficiency negatively
This makes utterly no sense and is actually 100% wrong. You need to look up the word efficiency and also have a look at the principle behind skimming (foam fractition). I highly recomend Esobal's book as a starting point. I also recomend a hard look at linear overflow lengths and how they relate to the ammount of protiens that end up in the water going to the sump. You will also find a lot of information in the wastewater industry that uses these same principles (this is us reefers stole the technology from).
Bean
tinygiants
New member
I am a water processor by trade. I use filters, carbon, resin, peroxide with UV, and evaporators. Most of what I do does not apply to our skimmers, but processing by dilution does.
Look at the original post about efficiency. You have to process water 9.2 times in order to get 99.9% totaly processed. If you only get 1/2 of the processable contaminants, you have to process the volume anther 9.2 times just to get back to par. I prefer to get more out in the first pass, cause whatever I let get by will take another 9.2 cycles inorder to get a shot at it again.
The single most efficient way to process is called single pass. In this method, all the dirty water starts in tank A, goes through a filter (skimmer, filter.....), and exits to tank B. The efficiency of that process is 100%. If the volume to process is 100 g, then you only had to pump 100 g to get all the processable items out.
If you use the dilution method (return processed water to the same source tank), you have to pump 920 gallons through in order to achieve 99.9% of the water processed.
Dale
Look at the original post about efficiency. You have to process water 9.2 times in order to get 99.9% totaly processed. If you only get 1/2 of the processable contaminants, you have to process the volume anther 9.2 times just to get back to par. I prefer to get more out in the first pass, cause whatever I let get by will take another 9.2 cycles inorder to get a shot at it again.
The single most efficient way to process is called single pass. In this method, all the dirty water starts in tank A, goes through a filter (skimmer, filter.....), and exits to tank B. The efficiency of that process is 100%. If the volume to process is 100 g, then you only had to pump 100 g to get all the processable items out.
If you use the dilution method (return processed water to the same source tank), you have to pump 920 gallons through in order to achieve 99.9% of the water processed.
Dale
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