Backyard Aquaponics
A place to discuss aquaponics

Hi all,

I have just purchase Joel's book/dvd today and am getting serious about setting up a system. The question I have is what folks are using as a grow bed media as an alternative to expensive hydroponic gravels?

One alternative I have been thinking of is a 50/50 mix of "Blue metal" road gravel and river sand. Would this provide a suitable environment to encourage bacteria growth? The main reason I ask is I can get the blue metal cheaply and the river sand for free...

TIA Kim...

Hiya Kim, yep just got your order today thankyou, will mail out this afternoon...

So far as media goes, I would be more inclined to go for the blue metal, river sand will become a bit of a problem getting into things and clogging up, sand and pumps don't mix well. You want a medium with a particle size of roughly 5-10mm for maximum benefit and growing area for bacteria.. Though I have even seen people use pine bark for a growing medium, not too sure how well that went though.. ..

Thanks for the tip Joel. I look forward to receiving the book and will try to refrain from asking any more n00b questions untill I have given it a though reading

Hi there,
I was firstly buying 6-12ml scoria (looks like terracotta coloured gravel but light like pumice) in 20 k bags for about $12 each, but i need about 3 bags to fill one tiny 50 L grow bed.
SO I just bought a tonne of the stuff- much cheaper at $175 for the lot and it was delivered to my door by Australian Native Landscapes. Now I have enough to fill plenty of grow beds and i can slowly build my system at my leisure with one cost out of the way. How cheap is your gravel? I would imagine you'll get great surface area out of it but is it not very heavy when wet? I couldnt use it as my grow bed shelving couldnt take the weight and it would blow my budget as I'd have to buy real heavy duty shelves.
Make sure your grow beds stands are safe and think of ways to protect your back when you're working with the stuff as you dont want to end up with a hernia shoveling heavy wet gravel for hours!
Good luck!

That sounds like an ideal medium Aeon.... And I guess with a ton of it you'll be able to do many small systems..

I have a quastion about your system, but I'll ask it back at your system thread..

This scoria sounds ideal. Will see if any of this is available by the ton in Brisbane. WHere do you live Aon.

Have now sourced some scoria. Had a really interesting chat to the landscape shop owner, who informed me he owned the biggest aquaculture setup in SE Asia, growing huge amounts of barramundi. Mostly we spoke about the bacterial growth on scoria (or any medium) and his concerns about collapse of the bacteria at a point where they had grown to a population that cannot be supported anymore by the nutrients supplied to them. Quite interesting.

Scoria here would be twice the cost of what AON would be getting down south. Also, the guy now oly supplies 10-14 mm stuff due to peoples complaints about too much dust in the 5-10mm stuff.

Would 10-14 be okay in scoria rather than gravel?

VB, my enderstanding is that the bacteria do not collapse when they out grow the nutients.

The just grow to the point that they are in equilibrium (cool, i got to use a big word ) with the nutrients.

Any more nutes than the bacteria can process and they begin to grow again to balance the system.

Any less and SOME die off to once again bring the system into ballance.

The only way that they would collapse is if you removed ALL nutes. Ie the fish.

This is why hospital tanks for aquariums SHOULD be kept with a fish or two in them or kept fed by drops of ammonia.

Oh, and don't worry about the surface area of a sizable amount of scoria not being able to support whatever colonies you need.

Trust me on this one.

Oh by the way, Good on ya to who ever it was that thought of scoria. As soon as i read it i thought "why didn't i think of that!" heaps cheaper than the hydro rocks and VERY porus and light. would probably just need to wash it very well.


Steve

Steve, what is "Scoria" - Is it something you get at a landscpaing place ?

Hi vegie boy,
I live in inner city sydney so theres no landscape supplies near me but Australian Native Landscape deliver stuff for about $50 so my scoria all up cost $255- still heaps cheaper than by the $12 bag. infact when i think about it i would probably easily use up $50 in petrol driving out to whoop whoop every month or so for a few more bags of the stuff each time I add on to the system.
Someone asked about using 10-15 ml scoria - i think that would be fine as its really "varigated" (is that the word?)- has lots of little ridges and bumps - so the surface area would grow the bacteria just fine. cant think of any reason why 10-15 ml would be a problem. I think the bigger the grow bed the better the filtration and my stuff is about 10 mls in a tiny system and the water is still crystal clear - still no algae blooms but its not in full sunlight.

Hope to one day escape the urban nightmare, build a massive pond with with a raised grow bed all around growing palms and vegies and stocked with perch and koi and have two goats called Terrence and Phillip. One day! Must first detatch husband's brain from online computer game.

Murray,

Yes a landscaping place should have it.

For a moment i thought iwas thinking of the wrong thing, but i did a web search and there is a WIDE variation in size you can get. A mate has it on his driveway, its probably the 10mm stuff. very red, porus looking and light. makes that "hollow" sort of sound when you walk on it.

I can see why the larger diameter variety might look like pea gravel.

Steve

I bought 5-7mm scoria from my local landscape supplier..two 50L tubs filled for $8. (had to fill the tubs myself)..I found the scoria to contain alot of smaller particles and dust...it was a pain in the a#%@ to first screen it and then flush the dust out of it (lots of labour). My 2 tubs worth ended as 1..Next visit I got the the smaller crushed gravel for $3 a tub..i found the gravel to have less particles but still the dust...So I have 1 tub with scoria and 1 tub with crushed gravel..The scoria seems to have more surface area and is lighter and better colour..(if that takes your fancy).

I've got a couple of pots to put indoor plants in on top of my aquarium, and got some perlite to grow in to avoid over weighty pots on top of the glass. The smaller bits perlite fall through the drainage slots on the bottom of the pot (was gonna sit them on rails on top of the tank and let the water drop straight in).

Should I put fly screen or something inside the bottom of the pot o. Will this clog up really quick. Should I just let the small bits fall through outside seeing it's such a small quantity?

Thanks

ahh one of the hardest things possible to come between a boy and his toys hehe good luck with the whole going bush thing. I also want to move at least further away from the city. Probably still within 2 hours. But some huge acerage and lots and lots of aquaponics

Cheers,

Duncan.

Hi Monya
Just let the the smaller particles fall thru..eventually they perlite will settle..

Hi Duncan..wouldnt it be great to have some acres and a aquaponic system that provides all your needs of food....I am living in a unit at the moment but still managed to get a small system setup..