RE: [compost_tea] Air pump selection

From: Robert Norsen <bnbrew_at_yahoo.com>
Date: Wed, 1 Oct 2003 07:56:49 -0700 (PDT)

No difference at all Mike. It was all in yur highschool physic class. Bob

Mike Bosko <mjbosko_at_jmtsystems.com> wrote:Bob, would it make a difference if one was to pipe the air through the bottom side of the tank using a fitting drilled through and a bushing installed; the air hose connected to that? Rather than push it down through the water from the top of the tank?
 
Just curious.
-----Original Message-----
From: Robert Norsen [mailto:bnbrew_at_yahoo.com]
Sent: Tuesday, September 30, 2003 11:50 PM
To: compost_tea_at_yahoogroups.com
Subject: Re: [compost_tea] Air pump selection


Stuart the absorption rate at higher pressures of deeper water drives more O2 into water at the deeper location. This would allow the slightly less air cause equal or more aeration in the deeper tank. The longer travel thru the water would also add to the effectivity of the air. So if the pump puts out nearly the same air at the greater depth go for the deeper tank. If the pump shuts way dowm at the deeper tank it will be quite reduced in the shallow tank. Select a higher pressure capable pump. The quiet modest cost aquarium pumps I use go to 50 " with no measurable change in volume. X

Stuart Baxter <stu.baxter_at_virgin.net> wrote: With the prospect of raising everyone's blood pressure.......
 
If you have a cylindrical tank 3 ft diameter and 3 ft high then the volume is Ht X pi X r2....I hope (well it is 05:15am)! giving a volume of 21.21 cu.ft.
If on the other hand you have a 3.66 ft diameter and 2 ft high tank the volume is the same, but you have 1 foot less depth to push the air down.
Assuming that an air bubble has only so much oxygen to give up does the second option (for wider and not deeper tanks) make more economic sense?
 
Any fluid mechanics experts out there?
 
night,night
 
Stuart
----- Original Message -----
From: David Loring
To: compost_tea_at_yahoogroups.com
Sent: Wednesday, October 01, 2003 4:43 AM
Subject: Re: [compost_tea] Air pump selection


There are pumps and there are pumps. For instance, the air pump that comes with the KIS 5gal brewer is fine for a 5 gallon bucket but it loses air volume quickly with increased pressure due to depth. My large Alita pump is less affected. I'm not real familiar with aquarium pumps but think most small ones are diaphram type and thus perhaps OK. Try blowing up the same bag in the bottom of a 5 gallon pail filled with water and see if you get the same result, at least that's one way to test it under some pressure.
 
Dave
----- Original Message -----
From: Robert Norsen
To: compost_tea_at_yahoogroups.com
Sent: Tuesday, September 30, 2003 6:27 PM
Subject: Re: [compost_tea] Air pump selection


Kirk and other would -be home brewer builders - One problem of procuring air pumps is that the pump ratings are not very reliable. At the shallow depth of the small brewers you can assume free air. No back pressure. To measure actual air delivered assemble your entire system including the diffuser you will use. Insert in a totally air evacuated plastic kitchen trash bag. Tape this and other openings of the bag securely so NO air can escape. Operate the pump for 1 minute. The bag will normally be partly filled. Instantly seal the air from escaping via the pump or other escape routes. Gently insert the bag into a rectangular box so you can take normal inch measures.
 
Inches cube divided by 1728 will give you CFM. The smallest CFM I use for 5 or more gallons is 1.7 measured this way. The pump is rated at 0.7 cfm! I have measured other .7cfm pumps that measured this way only .4 amd .28 cfm.
 
In operation the amount of air available has everything to do with the compost, temperature and nutrients that your brewer can handle in an aerobic condition. The gallons of the brewer has little effect. In other words you can have a 5 or a 15 g brewer with the same air if you use the same load of 'stuff'. The ACT will be somewhat less concentrated at 15 g but the total product is often double in the larger quantity even using the same compost and nutrients. That surprised me, too.
 
Another out for your small home built - You can add another aerator system along with the basic system to increase the capacity of your brewer, put the small brewer in a larger tank with increased compost and nutrients. So the day you want more ACT you can brew it for just the trouble of added pump and aeration system.
 
GOOD aquarium pumps are not cheese or unreliable. They are made to go for years at a time,, 24 hours every day and SOOOO quiet they don't bug you or your sleepy time pal. They use the amount of current of a small light bulb. Cost? less than $ 75.00
 
Just don't ask my name. X . . .

Kirk Leonard <kirk_at_oregonatural.com> wrote:
Goshdarnit, I messed up some numbers again, I think. 3000 cc's is about 183
cubic inches, .11cfm. Sorry. At .02cfm per gallon of water, still not
enough for 5 gals tea needing more than ambient oxygen, imo. Somebody
better with these numbers or a better idea what air/water volumes should be
should correct me.










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Received on Wed Oct 01 2003 - 12:18:47 EDT

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