Re: [compost_tea] Air pump selection

From: David Loring <dloring3_at_cox.net>
Date: Tue, 30 Sep 2003 20:43:27 -0700

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 vo=
lume 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 sma=
ll 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 dif=
fuser you will use. Insert in a totally air evacuated plastic kitchen tras=
h bag. Tape this and other openings of the bag securely so NO air can escap=
e. 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 inc=
h measures.
   
  Inches cube divided by 1728 will give you CFM. The smallest CFM I use f=
or 5 or more gallons is 1.7 measured this way. The pump is rated at 0.7 c=
fm! 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 co=
mpost, temperature and nutrients that your brewer can handle in an aerobic =
condition. The gallons of the brewer has little effect. In other words yo=
u 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 tot=
al product is often double in the larger quantity even using the same compo=
st and nutrients. That surprised me, too.
   
  Another out for your small home built - You can add another aerator syst=
em 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. S=
o the day you want more ACT you can brew it for just the trouble of added p=
ump and aeration system.
   
  GOOD aquarium pumps are not cheese or unreliable. They are made to go fo=
r 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 b=
ulb. 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 abou=
t 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 shoul=
d be
    should correct me.










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Received on Wed Oct 01 2003 - 00:40:57 EDT

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