Backyard Aquaponics
A place to discuss aquaponics

I'm currently constructing my home AP system (see link in signature). I am using a full IBC for my FT and a full IBC as a sump tank. I already have 3 GB's 4'x8'x12" which I plan to full with red cinder. My question is (all things being equal) how much grow media can I support with 1 IBC FT. I know fish density, plant density as well as type of plants will be a factor. But, just generally, with maybe 60-70 healthy 1lbs tilapia in my FT, how much could I get away with before I have to increase the size of my FT? Just in case I want to add another GB later on I want to know if it would be worth it. My fear is that I will eventually max out and all of the plants will suffer a lack of nutrient.

I know this question is 180 degrees out of phase with the normal thinking on this board. Seems like everyone wants to load as many fish as possible while not increasing grow media volume.

I think your line of thinking is very suitable for this forum, while it's true that a lot of AP enthusiasts are interested in fish stocking maximums, plant production needs to be at least half of the focus if not much more, because at the end of the day (year) plant to fish ration is going to have a massive contrast with plant production far outgrowing the fish.

Generally speaking you could go as high as, if not higher than a 2:1 GB to FT ratio. (2gal of Wet Media per 1gal of FT Water) a 1xIBC FT would allow you to have up to 500gal of GB. In my opinion, that would be maxing your capacity and you could run into some nutrient deficiency problems depending on the quality of feed your giving to the 70 Tilapia and at what rate your feeding them.

I personally think a safe ratio for fish and plant health would be around a 1.5:1 (375gal of wet media per IBC of FT water)

All that being said, when it comes to practical experience I'm not expert, but have done my research

Thanks for the response. I appreciate your input.

4' x 8' x 1' = 32cf x 3 GB = 96cf = 718gal / 250gal = 2.872 GB to FT ratio.

It looks like I've maxed out on GB before I have even stocked one fish or germinated one seed.
I guess I'll just have to run this setup for a while and learn the process.
If all goes well I'll have to seek out options for a larger FT.

I have 1 IBC fish tank with 80 fish.
I have 2 seasons with trout and silver perch living together - so 80+ fish in winter and then 50 silver perch in summer. I have 4x 1/2 IBC growbeds and 4x half blue barrels.

Plants are doing fine and there is little or no nitrates showing up.

Remember that you can run a system for awhile with no fish and it still works hydroponically - you can also run it for awhile without adding ammonia as the bacteria still do their thing - this is a mature system.
And you can always add an extra source of ammonia if there is not enough

You can also make another IBC fish tank inline of the same system - just don't make them overflow into eachother.

Also you can grow vege's that don't suck the system dry of nutrients - i.e. tomatoes are hungry

I have a 3:1 gravel to GB ratio.

I had to laugh at the all things being equal line.

It is quite presumptuous and chuckle worthy. I was trying to avoid the deluge of "but-if's" that seem to follow a question of this type.

I did consider the prospect of adding a 2nd IBC FT in the future. Perhaps splitting the pump line from the sump to both FT's and then feeding GB's from there. The look might get overly industrial in my backyard. I think by that time I'll either build my own FT or buy a 1000gal round rubbermaid tank from the local feed store. That's a bit off into the future. We'll see how it goes.

I like the go too far and then supplement if short of nutrients approach.

There will be times when nutrient supply is low anyway like middle of winter or after a big fish harvest so you may as well get a feel for it so you can do it confidently.

Aquaponics is so Zen.

Hippy

Actually my nutrients are rather high at the moment because my plants are not really growing. The poor dears are a bit cold.

After all said and done its a far better option to be nutrient deficient than too high in ammonia. Just go for it Squatchaponics!

The issue with not enough GBs is not the TAN. It is the lack of volume to process the solids or if there are not any other growing components like NFT or DWC then the build up of nutrients over time.

At the moment the nutrients in my system are climbing because it is so cold the plants are not doing much.

It's still a balmy coastal 14 degrees in my FT, you highlander you.

I was shocked, started adding more ammonia and away thing grow....very pleasing.