Backyard Aquaponics
A place to discuss aquaponics

Hi everyone,

So I have been lurking around here for a few weeks/months and recently I decided to 'come out of the woodwork'.

I will be constructing a small AP system in my courtyard which measures approx 2m x 10m, although I will only be using approximately 1m x 4m of this space.

The courtyard receives afternoon sun only (two story duplex faces south-east and this blocks all of the morning sun).

I picked up some Mary River pebbles today; I chose the "25mm" size over the "12mm" size as I thought that most of the smaller graded pebbles were way smaller than that.

I got them home and gave them a vinegar test and there are some very small bubbles coming off them, so I guess they aren't going to work. Question: does unsuitable media give off lots of bubbles in the vinegar test (like when you add bi-carb to vinegar), or just little bubbles (like when you have a bicycle tire with a puncture under water)?

I guess I'm asking if there are degrees of unsuitability, or if a very slight reaction is permissible? I have read a few threads that mention a PH drop-off a few months after cycling that is often augmented with shells as a PH buffer.


Anyway, I neglected to test the gravel before washing it so if it is definitely not suitable then I will have learned a lesson

They have some other sorts of river pebble out there so I can give them a go.

Some photos of the washing to finish up with;

Should be no problems with the Mary river stuff unless they added other material. How long did the bubbles last?

Maybe a couple of hours. They weren't bubbling in the morning, anyway.

I reckon for what I am doing, and the stage I am at (testing) I'll see how it goes, and later if the PH is too high can get some different stuff for my actual grow bed..

Images in case anyone can id some suspect rocks for me (that's a 25mm/3/4" pipe for reference):

Same stuff
I used and blind freddie, I think chainsaw used it as well. What landscape mob did you buy from. I get mine from Savage Landscaping in Landsbourgh.

I'd pick out those white bits... (they might just be quartz)

I think it was Coastal Landscaping in Kunda Park. The 12mm stuff was $99/m3, this larger stuff was about $120, but I paid $25 to fill one of the blue clams. Seems more expensive than others I have seen.

Rupert, I think ur right. Smooth, white, a little translucent. Quartz no good?

I'll pick it out.

Limestone would definitely be a problem... quartz not necessarily, it's Silicon based... and pretty hard....

Ask for the Mary River B grade 20/25 mm, about $78 m3. The good May river gravel is nearly extinct due do over production.
I pulled a hand full of the different white bits out and test with no reaction.

Yeah, it was Coastal Landscaping Supplies in Kunda Park.

He mentioned the Mary River stuff was more expensive because they had trouble getting it. I liked it cause it looked kinda smooth so hopefully easier on my hands and the plants.

I'm a bit restricted by what I can get cause I need to transport it myself (can't get a delivery dumped in the common area of my units), and I am transporting the loads in my little car and I don't want to kill the suspension.

The load to fill the clam was about 100 litres, and it weighed my car down quite a bit (felt like I was riding in a low-rider. heheh).

The B grade is not as smooth so plenty of area for the bacteria to develope. I do not find it hard on the hands and I am already doing my second planting

+1 here Sick Pupies, as CC bear said, I ve used the same stuff and it seems pretty good to me
a lot better than the drainage gravell I used in my first system ( I had to use acid over 6 months before the carbonates disaperared)

Also as CC bear said its pretty gentlle on your hands while your planting Etc.

Not that either of us has overly soft girlie hands of course
Well not me anyway.

I use blue metal in my system and just got a little metal hand shovel to not wreck my hands when I'm planting.

I have fairly soft computer nerd hands.

Lol not for long, should see my hands after three-four years of landscaping and a year of AP at my place. And I am dr computer nerd

to both of you

Work in admin (on computers), then I come home and research AP (on the computer).

Hmm, I forgot about maximising the surface area for the bacteria.

I will remember to get some rougher stuff next time.

I did some more vinegar testing on various rocks; there are some that start to fizz right away (still determining exactly which ones they are), but most = no reaction at all