Aquaponics Not Sustainable

I did the maths on aquaponics recently and found that the form advocated by gardening australia is probably not as sustainable as simply growing fish in farm dams. There is a high embodied energy per fish and plant grown and the capital investment never really pays off (things break before they've got their money's worth). It is very time intensive and requires high vigilance.

Looking at other people's experience with aquaponics makes me conclude that unless you run the fish right near critical levels of nitrate the plant growth is poorer than plants grown in the soil - certainly my soil grown veggies have out-performed all aquaponic grown plants I've seen (and I'm only a beginner are veggie growing). But when you run at high levels everything becomes very unstable - lots of fish deaths, lots of energy to move water around, expensive biofilters.

I thus suggest that 'living simply' and aquaponics, as currently practiced, are not compatible. Instead, use your fish tank as a rainwater tank, keep a low stocking density of fish in there, and use the water (retopped from your rainwater supply) as fertigation water. A small suspended sludge or similar system for oxidation of fish wee may be required.

I have taken this one step further, the water from the fish tank is boosted with a gentle manure tea before being provided at mains pressure using a spare pump. We irrigate all our plants with 'fish water' and get excellent results. Smartvalves, or the ceramic ooze pots as shown on GA last night, work well with such fertigation water (at gravity pressure). I have not had problems with biofilm clogging yet.