Water Efficiency of Aquaponics

[sillyoldfart]

Hello everyone.

As my name says I'm just a silly old ****** that's bored and got too much time on his hands.

Been doing lots of reading on this "aquaponics" subject, mainly because the use of water in my soilgardens has become harder and harder to justify with the water restrictions.

Having said that, I live at Swansea just out of Newcastle so it's not like we're short of water at the moment LOL

Looking through the posts I'm not sure that a lot of people are saving anymore water tahn using a soil garden.

Some people still seem to be watering pots and "growbeds" by hand and presumably letting the water soak stright through.

So question to people. How much water do you use doing aquaponics in say each week?

[GaryD]

Hi Silly,

Looking through the posts I'm not sure that a lot of people are saving anymore water tahn using a soil garden.

Some people still seem to be watering pots and "growbeds" by hand and presumably letting the water soak stright through.

So question to people. How much water do you use doing aquaponics in say each week?

All of the established systems on this forum use recirculating systems. Some of us use also use non-recirculating coco peat systems.

Both types of system use far less water than a conventional soil-based garden.

The amount of water that I use is dependent upon a range of factors including:

• the type of plants being grown.
• the number of plants being grown.
• the season.

I can specify exactly how much water I use because I record the amount that I add to my system every time I do a top up. This information is only likely to be useful for comparative purposes if we are comparing against a like-sized garden in a similar climate for which water consumption figures are known.

[sillyoldfart]

Ok. so it's only some people using the coco-peat in the place of soil.

I wondered what the benefits are of using this stuff, I've seen lots of it at Bunnings and nurseries lately.

You say it is more water efficient than a soil garden. ?Is this because it absorbs the water and holds it for loneger than a soil garden?

So you don't have to water as often and thus save water?

Guess using the fish water is just like using liquid fertilisers tehn?

[njh]

Ok. so it's only some people using the coco-peat in the place of soil.

I wondered what the benefits are of using this stuff, I've seen lots of it at Bunnings and nurseries lately.

You say it is more water efficient than a soil garden. ?Is this because it absorbs the water and holds it for loneger than a soil garden?

So you don't have to water as often and thus save water?

Guess using the fish water is just like using liquid fertilisers tehn?

This is a core question, and one that I've been thinking about a lot since I first read the claims that it is more water efficient. I think the main reason it is more water efficient than in soil gardening is that you do not have a huge sponge of neighbouring soil that is drying your plants out. Over a large enough area that border effects are insignificant this suggests that AP has a reduced potential for efficiency.

Another way in which the water becomes unavailable is by sinking below the root line. AP stops this by lining underneath the root zone with an inpermeable layer (the bottom of the grow bed). We could implement this on a fieldwide scale using modern membranes and suitably designed machinery but that may have other unintended effects.

The other ways in which water are lost are a) evaporation from the soil surface (could be controlled with mulch or a plastic film) and transpiration from the leaves, a fundamental loss the plants suffer when photosynthesizing. AP does not directly address these, although if AP is more dense - produces more plants per sq metre - then it make made greenhouse production more attractive.

AP does nothing for deep rooted plant's water use, which effectively use the enormous void capacity underground as their long term drought storage strategy.

I believe that non-recirculating systems are more water efficient than recirculating because there is less water movement, and hence less opportunity for water evaporation. (They are also more energy efficient, which in turn means less water use for the coal fired electricity)