Backyard Aquaponics
A place to discuss aquaponics

Hi

is there any other grow media that i can use in grow b ds otht than expanded clay and gravel. I spoke to one of acquaponics practitioner in melbourne and he suggested that using gravel is first generation acquaponics and we need to use something else for bacteria to grow. Is there anything better that could be used as grow media. I am still learning acquaponics so please bear with my question.


thanks in advance.

12mm - 14mm Blue Stone would be your cheapest.

(a). Did this Aquaponics practitioner define what he meant by "first generation aquaponics"?

(b). Did he provide you with any options to replace expanded clay or gravel?

(c). Did he explain why those options were better than expanded clay or gravel?

Melbourne acquaponics recently conducted an interview with citizen peng in which he recommended using sand. The reason he told was lot of surface area for bacteria, and mineral deficiency minimised.

the link is https://youtu.be/c389Q-bLpVE around 20 min or so. i don’t know how it wont end up clogging the system. just clarifying for my knowledge. i called him as well.

Can you get scoria in Victoria?

thanks for the answer i think the systems are called iavs.

yes scoria may be just did quick googling 14 mm size from some landscaping company. is it good?

Still curious as to what is meant by "first generation"

I watched a few of citizen Peng's vids 3 or 4 years back, pretty sure he has gravel in his GB's.

You could use sand in your GB's but it would need to be very coarse sand. You would get an increased bio-filtration capacity as opposed to using gravel, but at the expense of air spaces and GB longevity... It would clog up much, much quicker than any gravel GB.

Just for examples sake, many people have experimented with the two commonly available sizes of blue metal gravel (1/2" & 3/4") and the overwhelming consensus has been that the 1/2' gravel clogged up much faster than the 3/4"... So going down to sand sized particles would only amplify that issue greatly.

Even if the water was filtered to nth degree prior to it entering the sand beds, it would still clog much quicker than gravel simply from the build up of bio-film etc.

There have been studies carried out by smart people with letters after there names and they have determined that a gravel filled GB, filled to 300mm with expanded clay or similar sized gravel, will provide enough bio-filtration to support the amount of fish required to provide sufficient nutrients for that same square metreage of plants for most commonly grown veggies, and this has proven to be correct, so I don't understand the need to maximise biofiltration to such a degree that you would need to use sand.

If you did want to increase the biofiltration for the same square metreage of plants, you either (a). increase the gravel depth in the Gb's to say 400mm and stock the system with extra fish accordingly, or (b). add a stand alone bio-filter into the system, ie a 200L plastic drum filled with K1 media, that would greatly increase your safe fish stocking capacity.

thanks for the response. so 3/4 inch gravel should be good?

Yes, cheap (at least here in SA) and light

3/4" Blue metal works well. IMO scoria would be better a better option, and expanded clay the premium choice, if you can afford it.

The issues with blue metal are:

(a). It's weight. An IBC type grow bed, filled to 300mm with 3/4" blue metal and flooded to around 260mm with water, weighs 660-700kg. With 1/2" blue metal it would be even heavier. The same GB filled with expanded clay only has a combined exp clay and water weight of around 220kg.

(b). It transfers more heat to the water than exp clay and the surface of it gets very hot in summer.

(c). Difficult to dig in, plant seedlings etc.

Scoria's only issue of note is the digging part.

i would have gone with expanded clay as i am using it for my balcony system but the problem is whenever there is wind the big plants all fall down. Need something hard to hold them together.

if i go with ascoria how much would i need for a 10 feet long 1 m wide bed? Any help would be appreciated

thanks

Qatada, in order to calculate the volume of media required for your growbed the length, breadth and depth of the growbed are all required.

If you go with Scoria make sure its not "Recycled" as a risk of herbicide contamination .

I curse my scoria EVERYTIME I'm planting its hard on your hands and seem to dig a much bigger hole as it continually falls in as your trying to get a deep enough hole .

Still the cheapest option here as gravel with no lime is too far to cart .

I did have 20cm scoria and 10cm expanded clay. On the first harvest, they all mixed up but actually made it easier to dig in and put the seedlings.

Also if you end up cleaning the grow beds in coming years, expanded clay will let you keep your sanity while scoria is driving you mad so making some of the investment on expanded clay may be a good thing.