study on skimmer performance

[MarkoD]

Originally Posted by mat20040

yes,
the size also doesn't matter because the skimmers are on 24/7 the will skim but some faster and some slower.

Unless you have fish that constantly poop more than normal

[lastlight]

In many cases high-end means high-end pump. All these things blow bubbles but after dealing with the crap pump on my swc I'd rather have a solid pump getting me my 30% removal than my crap pump which I need to babysit to make sure it's even ON lol.

[ScubaSteve]

In a closed system with no TOC generation, a skimmer will only remove 30% and bigger skimmers will remove it faster, however, in the manner in which we run them (ie. continuously) the bigger skimmer WILL WORK BETTER because it will remove the labile TOC faster than the others. For example, if the rate of removal of the labile TOC is greater than the rate of labile TOC generation there will be no accumulation; however, if your skimmer is undersized you won't be removing the labile TOC as fast as they are generated and you will have TOC build up.

The rate of removal becomes even more important if you are running carbon dosing systems, such as vodka dosing, where you are converting the refractory TOC (that is otherwise not removed by a skimmer) to biomass in the form of bacteria. Since you would then be able to remove all of the TOC, not just the labile TOC, the equations they use become skewed. In this situation you will need an oversized skimmer to keep up with removal demands as removable products increase from 30% to anywhere from 65% to 80% (not all TOC is converted to biomass since the bacteria produce CO2 during metabolism, assuming all TOC is consumed by bacterial metabolism).

I wouldn't say that this article says spending a ton on a high end skimmer is a waste but (break issues described above aside) it makes the case for oversizing your skimmer. They didn't show suspended solid removal (ie. bacteria removal) in these tests at all. The high end skimmers that produce smaller bubbles in high quantities will remove organic suspended solids much faster than a POS skimmer will. So again, since we are running in a continuous manner, rate and size become important.

[SeaHorse_Fanatic]

Originally Posted by ScubaSteve

In a closed system with no TOC generation, a skimmer will only remove 30% and bigger skimmers will remove it faster, however, in the manner in which we run them (ie. continuously) the bigger skimmer WILL WORK BETTER because it will remove the labile TOC faster than the others. For example, if the rate of removal of the labile TOC is greater than the rate of labile TOC generation there will be no accumulation; however, if your skimmer is undersized you won't be removing the labile TOC as fast as they are generated and you will have TOC build up.

The rate of removal becomes even more important if you are running carbon dosing systems, such as vodka dosing, where you are converting the refractory TOC (that is otherwise not removed by a skimmer) to biomass in the form of bacteria. Since you would then be able to remove all of the TOC, not just the labile TOC, the equations they use become skewed. In this situation you will need an oversized skimmer to keep up with removal demands as removable products increase from 30% to anywhere from 65% to 80% (not all TOC is converted to biomass since the bacteria produce CO2 during metabolism, assuming all TOC is consumed by bacterial metabolism).

I wouldn't say that this article says spending a ton on a high end skimmer is a waste but (break issues described above aside) it makes the case for oversizing your skimmer. They didn't show suspended solid removal (ie. bacteria removal) in these tests at all. The high end skimmers that produce smaller bubbles in high quantities will remove organic suspended solids much faster than a POS skimmer will. So again, since we are running in a continuous manner, rate and size become important.

Thus endth the first class of ScubaSteve's water filtration tutorial. Please leave your apple for the teacher on your way out and don't let the door hit you on the @ss as you leave

Till next week's class

[MarkoD]

So a skimmer with better pump that creates finer bubbles is better? But what about the footprint and height of the skimmer? Would that create a huge difference?

[BlueTang<3]

What i got out of the article is BUBBLE KINGS RULE

[ScubaSteve]

Originally Posted by BlueTang<3

What i got out of the article is BUBBLE KINGS RULE

We call this selective information uptake. My girlfriend says I have this problem too.... "blah blah blah... sex... blah blah blah blah"

[ScubaSteve]

Originally Posted by MarkoD

So a skimmer with better pump that creates finer bubbles is better? But what about the footprint and height of the skimmer? Would that create a huge difference?

Does it it make a difference? It does, yes. But that's what I mean by "bigger" skimmer. The effectiveness of a skimmer is determined not only by the size and quantity of bubbles produced in the skimmer but also by the residence time of water in the skimmer.

The longer a particular parcel of water spends in contact with the bubble phase, the more organics are attached to the bubbles (thus increasing removal). The more bubble surface area, the more removal. The greater the separation of organic-laden bubbles from the water, the reduced chance of re-entrainment (thus increased removal). All of these have an effect on the skimmer performance. The "removal rate" that they present in the paper is an aggregate rate that takes into all of these effects.

And it IS possible to calculate the theoretical removal rate of the skimmer and how it changes with all of the different design parameters (maybe this will be something that I'll teach). But the number one parameter that will have the greatest effect is the skimmer volume. The bigger the volume, the bigger the throughput and the greater the residence time. A tiny skimmer with a huge pump that makes tons of bubbles isn't going to do much because the water won't stay in the skimmer long enough for it to matter (and you'll just fill your sump with bubbles).

[mat20040]

Originally Posted by ScubaSteve

In a closed system with no TOC generation, a skimmer will only remove 30% and bigger skimmers will remove it faster, however, in the manner in which we run them (ie. continuously) the bigger skimmer WILL WORK BETTER because it will remove the labile TOC faster than the others. For example, if the rate of removal of the labile TOC is greater than the rate of labile TOC generation there will be no accumulation; however, if your skimmer is undersized you won't be removing the labile TOC as fast as they are generated and you will have TOC build up.

The rate of removal becomes even more important if you are running carbon dosing systems, such as vodka dosing, where you are converting the refractory TOC (that is otherwise not removed by a skimmer) to biomass in the form of bacteria. Since you would then be able to remove all of the TOC, not just the labile TOC, the equations they use become skewed. In this situation you will need an oversized skimmer to keep up with removal demands as removable products increase from 30% to anywhere from 65% to 80% (not all TOC is converted to biomass since the bacteria produce CO2 during metabolism, assuming all TOC is consumed by bacterial metabolism).

I wouldn't say that this article says spending a ton on a high end skimmer is a waste but (break issues described above aside) it makes the case for oversizing your skimmer. They didn't show suspended solid removal (ie. bacteria removal) in these tests at all. The high end skimmers that produce smaller bubbles in high quantities will remove organic suspended solids much faster than a POS skimmer will. So again, since we are running in a continuous manner, rate and size become important.

IN your opinion what are the top skimmers ?

[Ryan]

So would an oversize skimmer body with a smaller pump (still big enough for the water volume) work better because water would spend more time in the skimmer?