Backyard Aquaponics

Grow Bed Area
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Author:  giljones [ Jun 22nd, '16, 22:14 ]
Post subject:  Grow Bed Area

Hello Friends,
Well I've done away with my barrel-ponic system and now I've got an active ibc tank system. One tank for my fish tank and one for my sump tank. I have 8 ibc grow beds 14" deep and added to that I've got one hydroponic system 2' X 6' X 8" deep. My question is : How many sq ft of grow bed do I have available for planting.

Right now I'm using gold fish to drive the system but I will soon switch to blue-gills. Thank you, Gil

Author:  dlf_perth [ Jun 25th, '16, 04:33 ]
Post subject:  Re: Grow Bed Area

Hi Gil, no takers on this one.

Hard question to answer because the simple resposne is "it depends on a lot of things", primarily:
(a) what veg you are growing and at what density (stems or plants per sq ft)
(b) how many fish
(c) the size of the fish
(d) what and how much you are feeding them
(e) size of your fish tank

as you say " I've got an active ibc tank system" I guess we are talking an IBC tote FT ?? ( 1000L / 260 US Gal)

As a first up guess 8 BC lid type grow beds would be too much unless you have high stocking rates.
certainly the goldfish will be struggling - fast growing food fish on a high protein feed tend to be a bit more ammonia productive (which leads to more nitrates to drive your system).

A normal IBC fish tank with 15-20 or so medium goldfish (10cm plus) will probably support 2-4 IBC top/half grow beds......depending on the veg. If you had a system with mainly lettuce, spinach, Asian greens etc (not too many heavy feeders) and were prepared to supplement with Seasol and some N/P liquid fertilser then this would get over the line - particularly if you have one of the three always in seedling stage (on a rotation basis). You can also afford to give your veg a bit more space and light.

Cannot comment on bluegill but suspect they will provide a bit more nutrient load. But doubt you would get too much more than 4 IBC half grow beds.

not sure how the hydroponic relates - presume that is separate to the system and doing its own thing.
you don't want hydroponic water mixing with fish as a rule.

In a literal answer to your question:

1 IBC top/half grow bed =900mm x 1200mm so basically 1m2 (~9-10 sq ft, but more like 8-9 sq ft in actual grow space).
So 8x8 sqft = 65-70 sq ft or so.

note however that a media grow bed is firstly a bio-filter with *wet volume* to #fish x kg (weight/size) as the typical consideration, with weight/size a proportional proxy for ammonia and waste generation
ie. bigger fish = more food = more waste so....
waste = function(fish size) with some species coefficient to cover weight-waste generated if you like maths....

Systems with moderate nutrient loads usually go for /end up around 1:1 FT to wet volume. For an IBC FT you will get that with 4 IBC half grow beds (that then presumes moderate to optimal stocking levels). That would probably be imit for an IBC. A proper large volume aquaculture type fish tank (2000L plus) could get higher levels approaching 2:1 (GB to FT), but we are not talking that here I presume. (Stuart Chignell - I think, and others - have discussed GB to FT ratios around the forum somewhere).

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