Aquaponics Digest - Thu 03/05/98
Message 1: re: Grow Beds
from PeterJTheisen@eaton.com
Message 2: Re: Grow Beds/Ratios
from PeterJTheisen@eaton.com
Message 3: Re: Grow Beds/Ratios
from PeterJTheisen@eaton.com
Message 4: Re: Grow Beds/Ratios
from "Lloyd R. Prentice"
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Subject: re: Grow Beds
From: PeterJTheisen@eaton.com
Date: 5 Mar 98 12:27:05 EST
At 02:38 PM 2/17/98 EST, Pete Theisen wrote:
>My long term answer is to go to a larger growing bed. I have obtained
some
>plastic containers that are 4'*3'*3' that I plan to cut down to provide a
>3'*4'*1' gravel bed, maybe even two of them. This will happen when about
>10 other jobs are done around the house. So, it will be a while.
>>Pete - where did you obtain these containers? What were they made
for/used
>>for? What did you pay for them? They sound ideal for small systems, and
I
>>know we have many potential users interested.
I believe the containers held a material called 'colloidal silica'. This
material is used by companies who do sand casting and I have seen them at
construction sites, I believe used by the masons. These containers are
sought after by the recycling firms since they are just the right size for
separating junk, and they are sized to fit on a standard skid. They have a
steel cage around them for support, they are not strong enough to hold
water at full depth without the cage. At 1 foot depth they seem to work
fine.
I was lucky enough to have a cousin inlaw that works for a firm and I get
their throwaways.
I hope this helps
Pete T.
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Subject: Re: Grow Beds/Ratios
From: PeterJTheisen@eaton.com
Date: 5 Mar 98 12:31:41 EST
Lloyd wrote:
Just to confirm my understanding, is the following analysis of a
proof-of-concept system correct?
Tank: 20 gallons
Beds: 40 gallons (4' x 3' x .5' filled with pea gravel)
Can support up to 10 1 lb. fish (Assuming 1 1b fish/gallon).
Questions:
-- How do you size the pump?
-- With beds filled with gravel, how much water would be pumped out of
the tank when the pump fully charges the beds?
My thoughts:
I would go with a larger fish tank and still keep to 10 pounds of fish.
This will give you a buffer in the system is something goes wrong. Also
with 10 pounds of fish in 20 gallons of water you will likely need to add
some supplemental aeration. I do. The spray of water in my system is
insufficient to keep the oxygen level high enough.
So for a smaller system I propose you go with a 40 gallon tank with 10 lb
of fish and a 40 gallon bed, actually I would make the bed 1 foot deep the
roots seem to go everywhere. What you can really control here is the
weight of fish you have, i.e. the amount of fish waste you have. You need
to keep in mind that small system can go to heck in a very short hurry if
something goes wrong. Large systems often offer you a little more time to
respond to problems.
I have used Rio pumps, the 1700, 2100, and the 2500. The higher numbers
are higher flow rates. They have been very reliable for me. They have a
shroud over the impeller area so small fish don't get ground up. I buy my
stuff from a mail order aquarium stuff company. It is much cheaper. I
think the company is called That Fish Place. I believe they have a web
site. As to flow rate I decide how fast I want the gravel bed to fill and
they determine the amount of water in the gravel bed and subtract the flow
rate I want out of the gravel bed and then buy a pump that at least goes
twice as fast. I can always put a valve in the line to slow down the pump
rate or increase the drain rate to adjust. As to the amount of water in
the gravel bed, I never actually measured it. I estimate that the gravel
takes up on the order of 65% to 80% of the space. So much depends on the
mix of sizes in the gravel. This is also the advantage of having a larger
fish tank, then less percentage of the water is removed with each pumping
cycle.
Hope this helps.
Pete T.
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Subject: Re: Grow Beds/Ratios
From: PeterJTheisen@eaton.com
Date: 5 Mar 98 12:53:34 EST
You wrote:
We generally do not recommend this volume of fish/gallon. For our system
we
stay closer to 1/2 lb./gallon, with 3/4 lb. as a maximum.
Tom's comment is that 1# fish would react poorly to this small volume. If
you're actually using this size aquarium, remember that the smaller the
system the more delicate the balance will be.
My comments:
I believe you need to keep in mind that the fish need to move water through
their gills to get oxygen. In small aquariums, maybe 20 gal, this can be
hard since they can't swim to far and water can't be kept moving easily.
This is why I have gone with parts of 55gal or larger plastic barrels. I
can get the water that returns from the gravel bed to flow in a circle and
the fish can swim in a circle around the outside the tank. This seems to
work fine and I believe I can hold more fish in small round tank than a
large rectangular aquarium. I suppose when one gets to 1000 gal the
difference may not be as great. But, for us people with small system I
believe it is very important.
Good luck:
Pete T.
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Subject: Re: Grow Beds/Ratios
From: "Lloyd R. Prentice"
Date: Thu, 05 Mar 1998 14:15:54 -0500
PeterJTheisen@eaton.com wrote:
> I believe you need to keep in mind that the fish need to move water through
> their gills to get oxygen. In small aquariums, maybe 20 gal, this can be
> hard since they can't swim to far and water can't be kept moving easily.
> This is why I have gone with parts of 55gal or larger plastic barrels. I
> can get the water that returns from the gravel bed to flow in a circle and
> the fish can swim in a circle around the outside the tank. This seems to
> work fine and I believe I can hold more fish in small round tank than a
> large rectangular aquarium. I suppose when one gets to 1000 gal the
> difference may not be as great. But, for us people with small system I
> believe it is very important.
>
Many thanks to both Paula and Peter for generous responses to my
questions.
Lloyd
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