Re: [compost_tea] Air pump selection

From: Stuart Baxter <stu.baxter_at_virgin.net>
Date: Wed, 1 Oct 2003 05:13:42 +0100

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 vol=
ume 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 sec=
ond 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 com=
es 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 i=
s less affected. I'm not real familiar with aquarium pumps but think most s=
mall ones are diaphram type and thus perhaps OK. Try blowing up the same b=
ag in the bottom of a 5 gallon pail filled with water and see if you get th=
e 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 procuri=
ng air pumps is that the pump ratings are not very reliable. At the shallo=
w depth of the small brewers you can assume free air. No back pressure. =
To measure actual air delivered assemble your entire system including the d=
iffuser you will use. Insert in a totally air evacuated plastic kitchen tr=
ash bag. Tape this and other openings of the bag securely so NO air can esc=
ape. Operate the pump for 1 minute. The bag will normally be partly fill=
ed. Instantly seal the air from escaping via the pump or other escape rout=
es. Gently insert the bag into a rectangular box so you can take normal i=
nch 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 am=
d .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 aerobi=
c 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 loa=
d of 'stuff'. The ACT will be somewhat less concentrated at 15 g but the t=
otal product is often double in the larger quantity even using the same com=
post and nutrients. That surprised me, too.

    Another out for your small home built - You can add another aerator sy=
stem along with the basic system to increase the capacity of your brewer, p=
ut 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 yo=
u 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 ab=
out 183
      cubic inches, .11cfm. Sorry. At .02cfm per gallon of water, still n=
ot
      enough for 5 gals tea needing more than ambient oxygen, imo. Somebod=
y
      better with these numbers or a better idea what air/water volumes sho=
uld be
      should correct me.










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Received on Wed Oct 01 2003 - 00:40:58 EDT

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