10 min $10 DIY aerated compost tea ACT brewer

[Bullfrog44]

Hey fellas...

I'm going to build the brewer featued @ the start of this thread.

What advantage do i get out of the vortex action vs. the straight drop like the one in in Microbeman's pic?

thanks for any input.

I believe the advantages to a vortex brewer is:

1 - You have zero dead spots in your tea. Every part of your tea is moving and staying aerated.

2 - I believe that the surface area that touches air both on the top of the vortex and the point where the vortex touches down and makes a slurping sound helps with aeration. I believe this action increases your o2 rates.

3 - Something about a vortex brings a smile to my face. Every time my brewer starts its vortex I get excited like a school girl. My wife makes fun of me for it, but I can't help it.

As soon as I finish harvesting my outdoor crop and get some more time on my hands I plan to buy a scope and do some side by side experiments on exactly what you are asking about. I want to see proof that the vortex helps produce microbial life. I have already made a 5 gal and 15 gal vortex brewer. I would like to compare those to what heady made in the first post and to a 30 gal garbage can with bulk head fittings. I normally don't grow right after a big outdoor season so I need something to pass the time.

 

[rrog]

I was thinking my picture would have the caption, "my bitches", so I guess "my children" is a little better.

I was going to suggest that 'till I read your post. Ha!

 

[SeaMaiden]

Bullfrog, surface area (of water) equals gas exchange, and the more turbulent that surface is, the more gas exchange can occur. It is only at the water's surface that O2 is exchanged with CO2 (and the colder the water, the more O2 it can hold). Shake it up, mang!

i was going to suggest disciples lol

Which is better than 'minions.' Though, I do have my own small cache of minions. It's always good to have a few on hand, just in case.

 

[Microbeman]

Bullfrog, surface area (of water) equals gas exchange, and the more turbulent that surface is, the more gas exchange can occur. It is only at the water's surface that O2 is exchanged with CO2 (and the colder the water, the more O2 it can hold). Shake it up, mang!

Which is better than 'minions.' Though, I do have my own small cache of minions. It's always good to have a few on hand, just in case.

Lets alter that to say it is only at the surface where CO2 can be released completing the gas exchange [eg. one gas exchanged for another] allowing the water to [in the case of bioreactors/brewers] become supersaturated [in some cases] with O2. If the CO2 were not released, there would be no room for the dissolved oxygen. However, there is a limited amount of infusion of oxygen from diffusers creating small bubbles [particularly at the depth of the vessel] and in the case of airlifts this infusion is multiplied by 'pressure' (not entirely the best word). At least that is my take.

 

[Microbeman]

Just to let you guys know, I have posted some of your photos on the compost tea forum so the folks over there can see how resourceful people can build inexpensive, efficient airlift brewers. I called you my students. I hope you don't mind. As we know you are also my teachers.

I get so sick to death of all the high-priced smoke and mirrors BS about ACT. That is another reason I posted the photos.

 

[StrapAssassin42]

ok Microbeman... not entirely sure im understanding your post correctly.

Are you saying that the 'pressure' created by the air lift is sufficient for oxygen infusion so the vortex isn't necessary?

It wouldn't be hard to alter the design on page one to make a vortex...ooor... do i need a hopper bottom bucket to make it work properly?

 

[rrog]

I believe Henry's Law states that the solubility of a gas is influenced by temp and pressure, and not the presence of another dissolved gas. I recall that the % saturation of CO2 does not affect the % saturation of O2. So a saturated solution of CO2 can still accommodate the dissolving of O2.

 

[Microbeman]

All I'm saying is that it is the airlift which is the greatest contributing factor in raising the dissolved oxygen capacity of an air pump. I believe I posted some math in this thread or the other tea thread. The vortex contributes some 'perhaps' by increasing the area of water to air interface but there could be a tradeoff if your return is not 'slapping' the surface. The real advantage to the vortex IMO is the thorough mixing of water, organic matter and DO2 leaving no dead zones.

Other$ believe that there i$ a my$tic quality created by the vortex or that it $omehow enhance$ the $tructural propertie$ of the water. [That is what your $3000 goes to when you purchase a store bought one;>]

 

[Microbeman]

I believe Henry's Law states that the solubility of a gas is influenced by temp and pressure, and not the presence of another dissolved gas. I recall that the % saturation of CO2 does not affect the % saturation of O2. So a saturated solution of CO2 can still accommodate the dissolving of O2.

Is that not applied to standard saturation (eg. at a certain temperature and altitude a body of water is only capable of a certain % DO2) and not super-saturation?

 

[SeaMaiden]

I'd have to go back a long ways to find the information (all my books are packed away), but I recall that, in aquatic systems at least, O2 saturation is tied to CO2 saturation levels, and these levels affect pH, and are affected by temperature as well.

Upon initial inspection, a benefit of the vortex could be that it creates a huge surface area by sort of stretching out the water and its contact time with air, along with all the turbulence it creates. Perhaps if there were riffles on the interior or water contact surfaces of the cone, that could further induce better O2 saturation (think rocks in a stream causing more turbulence). Ribbing, it's not just for pleasure.

 

[rrog]

I believe that the solubility of CO2 and O2 are independent of one another. A supersaturated solution of CO2 in water would not accommodate more CO2, but would accommodate more O2. Bubbling air in water would dissolve all the constituent gasses based on temp, pressure and solubility.

 

[Microbeman]

In ACT there is a lot of CO2 created by microorganisms which is why it is a battle to raise DO2. If the CO2 (& air) were not released at the surface the volume of the liquid would be increased considerabely. (eg. can of soda). I have a bunch of literature but hard to find right now. Supersaturation is very different than what is seen in aquariums, etc. It is similar to what is sometimes found near waterfalls, dams where often the DO2 is too high for fish.

I found this statement concerning Henry's Law;(??)
The number of molecules leaving the gas phase to enter the solution equals the number of gas molecules leaving the solution.

 

[rrog]

I think given that we are brewing air which is a mix of O2, Co2, N, etc and not pure O2, we ensure that we're dissolving all of those gases. Given the huge solubility of CO2 in water relative to the solubility of O2, I'm sure we're increasing the CO2, not decreasing it.

The dissolving of gasses does not change the solvent volume, at least in this bit happening here. The soda in the can has the same volume pre and post opening. It's just that the pressure drops when opened, and the CO2 concentration is much higher in solution, so it equilibrates rapidly and you have fizz.

Not that this matters, since we're also increasing O2 while brewing and that's all that matters. None of this changes the concept of brewing ACT and increasing D02. I only brought it up because of the CO2 reduction comment. No biggie that's for sure.

 

[StrapAssassin42]

you guys are awesome!! I love all the knowledge being thrown around!

Microbeman, wouldn't the ripples created by the vortex reduce the need for the 'slapping' effect created by a straight drop?

I wonder if I could put something (anything) partially in the way of vortex to create a disruption on the surface. just a thought.

 

[Microbeman]

I think given that we are brewing air which is a mix of O2, Co2, N, etc and not pure O2, we ensure that we're dissolving all of those gases. Given the huge solubility of CO2 in water relative to the solubility of O2, I'm sure we're increasing the CO2, not decreasing it.

The dissolving of gasses does not change the solvent volume, at least in this bit happening here. The soda in the can has the same volume pre and post opening. It's just that the pressure drops when opened, and the CO2 concentration is much higher in solution, so it equilibrates rapidly and you have fizz.

Not that this matters, since we're also increasing O2 while brewing and that's all that matters. None of this changes the concept of brewing ACT and increasing D02. I only brought it up because of the CO2 reduction comment. No biggie that's for sure.

Of note; When I measure, I measure O2 only. In a post recently it was noted that brewing ACT causes a rise in atmospheric CO2. The soda represented that it is under pressure and sometimes erupts upon opening (has a higher volume than it would without compressed/pressurized gases). When using a venturi in a 1200 gallon brewer if the return line is submerged the tank swells and overflows with a lesser DO2 reading; if the return line is suspended over the surface causing the surface tension to be broken (thereby allowing release of CO2? Gas exchange?) the tank does not overflow and the DO2 reading is higher.

It is my conjecture (accepted by patent scientists for whatever that is worth) that the O2 displaces the CO2 sort of; the expelled CO2 makes more room for O2; maybe incorrect but it seems to work.

 

[Microbeman]

Microbeman, wouldn't the ripples created by the vortex reduce the need for the 'slapping' effect created by a straight drop?

Who knows?

 

[rrog]

I have no doubt that enormous respiration would / could CO2 saturate the tea to the point where excess is released into the air.

Not to argue, but if anyone is curious and were to read up on this, I'm quite sure they'll find what I have stated is fact.

 

[StrapAssassin42]

well rrog, i hope to be able to back you up after reading the book you recommended. ordering it from amazon now...thanks again!

 

[rrog]

Hey strap. You won't find this info in Teaming With Microbes. The book is specific to the micro-herd / root interactions in the rhizosphere. A really great read

 

[Microbeman]

Have you thought about why it is called the gas exchange? I'm sorry if I have been unable to explain myself properly. A gas exchange can occur at the interface between a liquid and gas. This is like in our lungs, where CO2 from our blood is exchanged for O2. At this interface there is a surface tension similar to that between water and air. As a function of pressure across this barrier one gas is exchanged for another. In the case of ACT and aquariums CO2 waste is exchanged for O2 We enhance this by breaking the surface tension. Water has a stronger surface tension than many liquids, including oil. I believe that this forms the basis of provision for DO2 in the aquaculture world. Seamaiden please correct me if I am mistaken.

well rrog, i hope to be able to back you up after reading the book you recommended. ordering it from amazon now...thanks again!

Is there a recommended book on the subject?

My records are in a mess and all I could find for literature online was some university course material and aquarium stuff.

I do not believe any of this contradicts Henry's law (which is based on temperature strictures and pretty standard pressures?)