Backyard Aquaponics
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I'm trying to establish the expected PH level from pea gravel.. (is it the same when using cracked gravel) As the cost to establish is considerably cheaper for this newbie.
Thanks Willaquapon

I didn't have a ph problem with pea gravel (this is the round brown stuff? in WA).
As far as I remember Burnsy had it in his school project so his comments would be a lot more useful.
From memory there was a study done that showed that pea gravel, for a while, reduced P or K I can't remember which but I don't think it was an ongoing problem.

No obvious problems..That's a good start.Many thanks for your reply.

Hi Wa



The geological source of your gravel detremine the acidity, here (Norway) all quarries, mines etc. have some sort of geological survey & monitoring procedures, as part of environemental obligations/regulations........
So, the source/distributer of the "cracked gravel" and the public geological survey would now the exact acidity and long term acid leackeage effects. Same or simmilare with river peagravel

this link:
https://www.dlsweb.rmit.edu.au/conenv/e ... goverv.htm
Overview: Acid Drainage: Sources, Impacts and Responses
Dr Graham Taylor, CSIRO Land and Water, surveys the issue of acid drainage in Australia

cut/paste:
What is Acid Drainage?

Acid drainage is a naturally occurring phenomenon where sulphide minerals in rocks, in the presence of oxygen and water, oxidise to produce sulphuric acid.

The chemical process has two environmental consequences: the sulphuric acid can get into streams and rivers, lowering their pH and damaging their ecologies and killing plant and animal life; and the acid can leach metals from rock, releasing them into the environment as contaminants.

While it is a naturally occurring process, the speed of acid drainage increases markedly when the surface area of sulphidic rocks is greatly increased by fracturing and crushing as part of the mining process.


I found googeling "acid rock drainage australia" so I'm sure you have some sort of simmilare, I would be surprised if the expected Ph level is the same thruout Western Australia on cracked pea gravel, but you should be able to get specifics on the gravel you have available localy. Do to the weight it is usualy a local source


cheers
edit to add this pdf ( from page 24)
3.1.5 Experiment 3 – variations in pH A wide range of pH conditions can occur in natural water systems (Wetzel 2001). Generally, pH is between four and nine (Hemond & Fechner-Levy 2000). In some situations, extreme pHs will occur. For example, acid mine lakes are known to have pHs as low as two (Hemond & Fechner-Levy 2000; Boine et al. 1999; Kleeberg & Gruneberg 2005) and alkaline lakes may reach pHs above ten (Hemond & Fechner-Levy 2000).
Three pHs were tested for their phosphorous uptake: 2.3, 4.6, and 10.6. pHs were chosen for experimental reasons. The three pHs covered the broad spectrum of conditions which laterite material may be placed in.

http://www.google.no/url?sa=t&rct=j&q=& ... GQ&cad=rja

Well if you want to be technical about it.

http://www.uwa.edu.au/__data/assets/pdf ... __2007.pdf

Most people complain about the fines but it seems to be a good growing media once it has settled in.