Pushing the limits on bubbles in skimmers

[crn005]

According to calculations, the most amount of ozone that can be pumped into a skimmer chamber is 13% (Escobal). What happens when you push that thresh hold? I know the bubbles will start to merge together, but what happens to the amphipathic molecules? Are there any adverse effects of running right at the 13% maximum?

 

[crn005]

Eh?

 

[Timber77]

escobals 13% comes from air in the skimmer not ozone.

 

[Crowed]

im not sure about 13%, but there is a maximum amount of air what we can pump in skimmer body before we get too much. like you said, bubble will merge together(less surface area-air/water contact-less skimming), also we get more turbulences, so probably some molecules will not be skimmed as it would in less turbulent ambience.
-and even if we could push the certain(max?) limit of air volume in skimmer body to get better skimming how to achieve that? we cant use water pumps(with more air flow/more water flow). air pumps? but we must achieve enough water flow too..and with all that amount of air what about skimmer neck then? diameter should be wider or foam will rise too quickly..but too wide neck isnt good thing if we dnt have enough organics in water to fill it...

 

[crn005]

bubble will merge together(less surface area-air/water contact-less skimming), also we get more turbulences, so probably some molecules will not be skimmed as it would in less turbulent ambience.

I understand that there would be more turbulence and it would cause some molecules to break lose from the bubbles. However, wouldn't the overall increase of bubbles compensate for that? Wouldn't the molecule attach to another bubble once it's broken lose? As far as surface area, I guess you have a point. There could be adverse effects the farther you push it.

and even if we could push the certain(max?) limit of air volume in skimmer body to get better skimming how to achieve that? we cant use water pumps(with more air flow/more water flow). air pumps? but we must achieve enough water flow too..and with all that amount of air what about skimmer neck then? diameter should be wider or foam will rise too quickly..but too wide neck isnt good thing if we dnt have enough organics in water to fill it...

We could push the limit on air in the chamber using good ole air stones. The counter-current, air-stone-driven skimmer is a timeless classic that is overlooked these days. And yes, the neck would have to be sorted out for it to be efficient. I was just curious about what happens inside the chamber.

escobals 13% comes from air in the skimmer not ozone.

Yeah, sorry. I use them interchangeably sometimes.


So, I propose another question. How do you calculate the volume of air in your chamber at any given moment? Do you take the lph of air that your pump/stone introduces and then divide it down to the second?

 

[Crowed]

some molecules will attach again, yes, but some need longer air/water interface and maybe will leave skimmer before that happen again.
you can calculate body volume and use airflow meter to calculate amount of air passing through, or (if air driven) you can try to close water in/out holes and measure water volume after air is shut. but, you can not measure size of the bubbles..

 

[crazzyreefer]

The Bubble rise is about 20' before surfactants are developed on a bubble to allow for collection, this is the largest mistake perpetuated on the public by equipment designers, since only a 2' skimmers is all most people have room for, equipment makers, fracture the foam, but in doing so all those tiny air bubbles do not have any skin, and with out the skin they do a poor job collecting waste, its above 30' that a skimmer truly does what the equipment was meant for and that is removal of all waste. so in this case less is more. Much of this research is done already by water treatment plants, and can be found in white papers. As for ozone for skimming it is a better method, but still will need the same bubble rise.

 

[behlke]

Crazzy -

Twenty FEET of water before the organics adhere to the bubbles?! Then what is all of the stuff that collects in my little skimmer cup after 12 inches of interaction? Please elucidate on the need for 20 feet of water.

 

[crazzyreefer]

If you notice what collects on the side of the skimmer neck and have it processed, you will find the organics and un-organics higher in all organics and un-organics on the neck than in your cup, This is one of the benefit to Wet necks and wet skimate, this is the surfactant bubble tension that burst prior to leaving the skimmer, If you went to a beach and that heavy foam skimmate got on you it would be hard to get off this is because the bubble have reteach optimal rise and are now fully coated, it is after this period that the bubble rapidly collects organic and un-organic matter, prior to that a bubble rising and colliding with another will strip each other of surfactants , Its a shame that Escobals wrote that his theory was law, they are not, He took a lot for granted, and is easily disproven in a lab or when applied in a real world environment. Bubble rise rate are subjective in a skimmer body, in a tube with a single bubble, The rise rate can and has been calculated, but that all depends on size, the tinyer the bubble the slower the rise rate, also once the surfactant layer is adequate the bubble quickly starts to adhere to all compounds in the water column, this in turn slows the rise rate again, and at the last level they are barley floating to the top of the water column when the are fully loaded,

A skimmer isn't more productive by the turn over rate nor the amount of foam it makes, as it is a some point stripping the surfactants off every bubble it makes, collectively the surfactants do rise to the neck of the skimmer and it is the reason why the skimmer neck catches all the organics, and yes some does go in to the collection cup, but most just go back into the tank. recycling the water through the skimmer multiple times does vary little due to the loss of surfactant build up on a bubble, it is only in the last stage of bubble rise that it acts as a stripper in a skimmer. If a skimmer is 10% effecive at removal, it will not be 100% effective if the water was to go through the skimmer 10 times, you would get less and less due to decrease efficiency. Most skimmers are between 2% and 13% effective, the skimmer I built reaches 88% max, but normally its right around 72%

In the skimmer I run I don't have 30+ feet, my wife would kill me If I dug down a shaft in our home for a bigger skimmer...(I have thought about it) so 24' is my max, (but honey all I need is another 6-9 feet) and at his point, I have to have compressed air to blow the fully formed bubbled down the drain, at times the foam will not break up and goes out like smelly soap bubbles from my roof as they bubble out the drain vents.

 

[Crowed]

which method you use to calculate removal rate?
-how much energy i will need to run such tall skimmer? even if removal of all waste is possible, wouldnt water change be much better and less expensive method for that in most tanks?

 

[crazzyreefer]

I use a Oil-less air pump (food grade) used for large soda dispensing operations. I tried large aquarium pumps and they couldn't do much more that 15' of water pressure. Costs.... well yes I could replace 100 gal a day, but my time is also considered as money. Is it an expensive system, yes. I no longer look at my electricity bill, it goes directly through bill pay.

I have a calculator I have built using the findings from many of the brands of skimmers, I take one gallon of tank water dehydrate it and then remove the salts, and analysis and weigh the remainder. Then compare it with one gallon of skimate done the same way. calculate this against the time it takes to collect a full gallon of skimate and the amount of non-organics it is stripping out of the water column. I have a friend that is a engineer and owns a testing service and contracts for a large wast treatment facility. He does all my testing. I find most HOB are just about useless, lower than 2% Even some of the big RK2 are not that great, I was told recently that they now only recommend the smaller RK2 units for keeping crabs and fish at your local market and not reef tanks. These units start at about 5k and reach over 50k in pricing

 

[ksed]

typically RK2 skimmers regardless of the size are based on a 1 or 2 minute dwell time respectively.
Do you believe that is not enough? It must be better than the skimmers typically used today which are no more than 20inches?

 

[crazzyreefer]

yes they perform better, but not over 25% and some under 15%

 

[crazzyreefer]

When I speak about height its bubble rise in non-colloidal water column, a skimmer may be 20" but only have a 10" rise or less, and that may not even be non-colloidal.

 

[ksed]

Kind of like a beckett or downdraft where the water height is low but it has a tall foam head?

 

[ksed]

If I understand this correctly, the air bubble's in the water column can have a long contact time or a tall reaction chamber but as long as it's in contact with the water it is irrelevant? it has to be a dry foam?

 

[crazzyreefer]

If I understand this correctly, the air bubble's in the water column can have a long contact time or a tall reaction chamber but as long as it's in contact with the water it is irrelevant? it has to be a dry foam?

Sorry if it wasn't clear, The Dwell time in contact with the water is the most important and the dewll time starts once it no longer colloidal with other bubbles. The foam will stay fully formed and even dry in bubble form if the bubble rise/dwell time is correct, The amount removed and the types of Organics and non organics removed increase with Dwell time.

 

[Sorry]

interesting... can we see what your skimmer looks like?

 

[crazzyreefer]

I will try to post pics but Its so tall it just looks like pipe...

 

[Big E]

Getting back to skimmers we're going to actually use, under 3 feet..........I've been looking at new skimmers and the physics just don't add up.

They keep getting smaller and smaller claiming less turbulence with the plates. That's fine I guess, but the bubbles go straight up and out and to the top of the skimmer in seconds. I'm wondering just exactly where are the bubbles grabbing these dirt molecules in a one pump internal skimmer that has a small 6" diameter and the reaction area is maybe 15" at best. These are your basic 300g+ rated skimmers.

My friends Aquamaxx Cone S2 all the bubbbles are lined right up in a big column and they go right to the top immediately.