Calculating bed size

[rangebob]

I'm getting confused by the calculation required to see if I have enough bed space. I have a 6' round kiddie pool 18" deep it can hold around ~300 gallons but I'm keeping it about 3/4 full so around 250 gallons. Currently I have about 2 dozen goldfish in there. This is just my trial system to see what and how it works.

I'm using 3' x 2' x 8" deep concrete mixing tubs as grow beds. Currently I have 2 but want to expand further and it is in the plans for more beds. I'm thinking I'm under the suggested amound of grow space.

[bcotton]

36'x24'x8" = ~30 gallons.

I wrote a little quick calculator app that can help quickly calculate volume of cylinders, half cylinders and rectangular shapes. http://www.hoppykoala.com/systemCalc.php

currently there's no save or link feature, i just use it when i am brainstorming designs and want to get a rough idea of how much volume it is.

Inputs should be in inches output is gallons and cubic yards since substrate is usually purchased by the cy~

brian

[rangebob]

So I'm guessing you are saying that I am way under what I sould be. I'm only turning over 60 gallons. I know that the ammonia is a little higher.5-1 from the test.

[bcotton]

Really it depends.

Some people say a good rule of thumb is 1:1 fish tank to grow bed ratio but it depends more on your fish load (how much ammonia you are producing). Personally, with two 30 gallon grow beds, i would keep about 5 lbs of fish. i would consider 8 lb fish to be max. This is based on roughly 6 gallons of media per 1 lb of fish fish (i'm assuming the grow beds are only 80% full)

this is a conservative guestimation.. I have little doubt experienced people push their mature systems much denser.

how did i get 6 gallons of media per fish? This is just a guide i personally use and isnt at all a hard rule. It's based on the idea of 1 lb of fish for every 3 gallons of water for every 2 gallons of media (1x3x2=6). Outside the calculation i really dont care how much water is in my system, in your case it could be 60 gallons, 300 gallons or 1200 gallons, your theoretical max fish load doesnt really change much.



brian

[keith_r]

+1
stock to the amount of filtration you have..
in a mature system i'll push about 25-30lbs of fish for every 100gal of gb

[jackalope]

We've always gone by the Gallon method - 2 gallons of GB to 1 Gallon of FT. Also, there are many opinions on a formula for a minimum of x# of gallons per lb of fish as seen here Clik
We always used 1 gallon per pound as a rough guideline - when they are younger, that works fine, but as they grow older and without expanding our growbeds, we might go as much as 4 gallons per pound depending on the amount of ammonia, etc. produced - and, as has been said, the key is filtration/oxygen - If you don't have good enough filtration/oxygen supply, 10 gallons per pound may not be enough

Since I mentioned oxygen, there was some posting about oxygen a couple of years back - I had found an article that showed that water dropping into the FT provides better/more oxygen content than air stones. For that reason, we bought a small fountain pump and created a fountain in the center of a pool as mentioned above - no airstones - and never saw any fish coming to the top of the tank for anything but food - if you see them coming to the top of the tank/pond, they may be starved for oxygen