Comparison between dirt grow beds and different media in aquaponics systems

The parameters of this trial are as follows.

Four dirt beds 1mx1.2m each to replicate the above tank grow beds on four IBC’s and filled with differing ‘dirt’ media. Two beds in each planted with lettuce and the other two with radish. Reason being they are shallow rooted and cannot take extra nutrient by sending down a tap root in the dirt grow beds. The IBC beds are 30cm deep and would closely replicate the dirt beds.

Water is closely counted as is rainfall. The only nutrient additive is Seasol as there are no fish used or fish feed to confuse results.

What produce grown will be recorded, weighed and taste tested to determine which bed is the best.

Due to weather conditions the dirt beds were prepared and planted two weeks before the IBC beds became operational. The IBC beds have a submersible pump that sends water the each bed every hour for 15min during daylight hours, 6am to 6pm. Thirteen rotations. These beds then auto siphon back into the tank below and all tanks are interconnected to ensure a floating water level. Over time each bed has developed it’s own siphon cycle time due to different density of the differing grow bed media.

Photo shows the dirt beds and IBCponic beds prior to seeding.

This next bunch of photos show the progression of the ponic beds compared to the dirt benchmark. Keeping in mind the ponic beds were two weeks behind in getting established due to weather extremes.

August 26

Watered dirt beds, 48 lt.

August 28

Watered dirt beds, 48 lt.

August 30

Watered dirt bed, 48 lt.

September 2 2012

All beds and water now 7.2. Added pumping system on a timer to fill aquaponic grow beds and auto siphon out into tank below, total 2000lt. Siphon cycling about once every 15 min, daylight hours only 0700 to 1900. Added uncut IBC with 500lt to enable the four cut reservoir’s to balance better.

September 4

Watered dirt beds, 30 lt. Some radish emerging. Need to find way of keeping dogs from enjoying the mud and disturbing the beds.

Aquaponic beds cycling the grow beds nicely water clearing as I did not wash the scoria prior. Main reason is to give the compost worms something to digest as the nitrification bacteria grow in numbers. Have joined all four lower tanks with bulkhead fittings so the water level will “float” enabling one pump to supply all four grow beds with water and floating water level in the fifth reservoir. Will seed the beds tomorrow.

September 5

Unable to seed aquaponic beds due to gale force wind, dust storm and occasional driving rain.

September 6

Dirt beds damaged by barricade being blown down and flapping over the emerging seedlings. Other damage on farm includes front biodiversity sign star post snapped off.



Rainfall on site from August 25 is 453 millimetres.

September 7

Aquaponic beds cycling now once every 45 minutes. Dirt beds showing radish emerging, will seed aquaponic beds this weekend.

September 8

Seeded grow beds with lettuce mix and radish mix, added compost worms. Watered dirt beds 48 lt. No nutrient added to date.

September 9

Lettuce emerging in dirt beds.

September 12

20ml Seasol solution added with 6lt water on each dirt bed, total Seasol 80ml, water 24lt. 20ml Seasol added to each ponic bed, total Seasol 80ml. 1mm rainfall.

September 14

No watering need.

September 18

Warm weather, watered dirt beds 48lt. Some minor weeding.

September 22

Minor weeding in dirt beds, ponic beds still emerging.

September 30

Ten mils rain in last week, no need for any supplemental water. All beds doing well.








October 1

Gentle southerly breeze, will do a few 20lt glyphosate sprays away from surrounding pea crop.

October 2

Dirt beds given 48lt water. Love the smell of freshly wet dirt!  Some minor weeding undertaken. Ponic beds progressing well. Hot and dry.

October 4

Dirt beds given 48lt water. Hot and dry.

October 5

Hot and dry, expecting 5 to 10mm rainfall tomorrow, no watering in expectation.

October 8

Registered 7.8m rainfall. Weeded dirt beds for an hour. Ponics cycling well.

October 12

12.9mm rainfall recorded in the last week. First harvest of dirt beds.


October 13

Gordon helping harvest lettuce.

Watered 48lt on dirt beds. End of trial for LG. Will continue monitoring.

October 14

Seasol applied to all pots and grow beds as well as dirt plots. 40ml per 9lt water x 3 times for house pots and beds, 30ml per 6lt x 4 for dirt beds at dome, 30ml per ponic bed x 4.


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