RE: [compost_tea] Air pump selection
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 - 12:18:38 EDT
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