Re: [compost_tea] Air pump selection
Robert - I suppose a funnel over the air stone and a short pipe to the surf=
ace would do it. I was just trying to caution people not to assume any pum=
p they buy would not be affected by the pressure of water, even in a 5 gall=
on bucket. I know it is not a lot (1 psi will push air down through 2 feet=
of water) but it is worth noting if you're using low cost pumps. Given, e=
ven cheap aquarium pumps are probably designed to push water down a few fee=
t. I just didn't want anyone to be surprised if no air came out of the bot=
tom of their pipe.
Dave
----- Original Message -----
From: Robert Norsen
To: compost_tea_at_yahoogroups.com
Sent: Tuesday, September 30, 2003 11:35 PM
Subject: Re: [compost_tea] Air pump selection
David you calculate the back pressure at any depth and calculate the resu=
lt. If you want to measure actual rate of flow at depth, release water at =
the intended depth but collect it at the surace. Easily done. I will let =
you figure our how. X.
David Loring <dloring3_at_cox.net> wrote:
There are pumps and there are pumps. For instance, the air pump that c=
omes with the KIS 5gal brewer is fine for a 5 gallon bucket but it loses ai=
r 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 procu=
ring air pumps is that the pump ratings are not very reliable. At the shal=
low 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 e=
scape. Operate the pump for 1 minute. The bag will normally be partly fi=
lled. Instantly seal the air from escaping via the pump or other escape ro=
utes. 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 u=
se 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 th=
e compost, temperature and nutrients that your brewer can handle in an aero=
bic condition. The gallons of the brewer has little effect. In other word=
s you can have a 5 or a 15 g brewer with the same air if you use the same l=
oad 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 c=
ompost 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 add=
ed pump and aeration system.
GOOD aquarium pumps are not cheese or unreliable. They are made to g=
o 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 lig=
ht 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. Someb=
ody
better with these numbers or a better idea what air/water volumes s=
hould be
should correct me.
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Received on Wed Oct 01 2003 - 12:18:49 EDT
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