Backyard Aquaponics
A place to discuss aquaponics

So, is the gallons relating to the total volume of the grow bed, or the amount that actually floods? I read somewhere that 60% is taken up by media, and only 40% is flooded with water. So, am I over thinking this... I have a feeling it's just the base overall volume. Yes?

Yep....

Thanks, EB. Figured I've been over thinking... I kinda do that a lot
Keep it simple, stupid... remind myself daily

Thanks!

Hi just want to verify this with 2:1 GB:FT ratio

so if the recommended density is 3kg / 100L is this GB or FT Volume?

and planning on harvesting @ 1kg that would mean 3x fish per 100L
below are based on FT volume

18 000L GB, 9 000L FT, 270 kg / 270 Fish
feeding rate of 1% = 2.7kg per day

and planning on harvesting @ 500 grams that would mean 6x fish per 100L
18 000L GB, 9 000L FT, 270 kg / 540 Fish
feeding rate of 1% = 2.7kg per day

but what happens when your not densely packing the tank ?

18 00L GB, 22 000L FT 270 kg / 540 Fish
feeding rate of 1% = 2.7kg per day
technically its the same amount of waste?


my original goal was 600 fish in 22 000 Tank
Discount applied after 500 fish plus they are shipped in 200 lots
( pretty sure it worked out same price as 500 ROFL )
and 22 000L tanks are the best bang for buck tank size I can find here


but if I use the 20~25kg Density rules I get different Qty's
which rule is best to use 3kg/100L or 25kg/m3

@ 1kg Fish weight 3kg/100L capacity 25kg/m3 density
FT Capacity density
6000 180 150
9000 270 225
22k 660 550

its seems I can grow 600 @ 20kg Density up to 730 grams in 22 000 L tank
but to do that I need to up my GB to 44 000L ?... mmm

or should I stick with using GB as the limiter and running 250~400 fish @ 9000L volume water ?



My Grow beds would only be around only 18 000L ( 18x IBC cut in half for 36 beds ),
but I was also using NFT/Raft systems in the mix along with an under Gravel filtration system inside the tank itself that's another 9 sqm around 10cm deep 1 Cubic Metres = 1000L

does anyone have an NFT equation or an bio filter equation to fill in the missing ratio


*edit* Think I worked it out use density based what ever the bottleneck is in this case on GB

so 18 000L is my GB limit

500g fish @ 20kg / m3 = 720 fishies
1kg fish @ 20kg / m3 = 360 fishies

so my 600 fish @ 600g should be fine ?

I think you have it figured correctly: the growbeds can handle a certain max amount of waste at optimum conditions. This can be approached in several ways.

Important: you also need to remember that the growbeds are going to take some time to develop the microbiome that will best handle the waste stream. This microbiome will vary with temperature, feed, etc, etc, etc.... so sudden changes in load or other conditions can be problematic.

Your system sound fun!