Backyard Aquaponics
A place to discuss aquaponics

Hey everyone,

A mate of mine came over on the weekend and said he knows someone who has a crap load of those white rounded small stones people often use out the front of their houses, etc.

Does anyone know if these would be suitable for grow media? He has offered them to me for free!

I am trying to get the actual name of the pebbles so I can be certain what they are.

Cheers.

so long as they are not marble or limestone they should be fine. Free is always good so long as they haven't been getting sprayed with oily chemicals. Of course the size of the pebbles is kinda important but many people like to use larger rocks around the drains and in the bottoms of deep beds.

Rounded stones are nice for your hands. Even marble or limestone is probably ok as long as it is a minority of your gravel: my system sits at 7.6 and probably has some in it. One can test with hydrochloric acid. What size are the stones?

I will try to get a photo in the next couple of days.

A mate of mine knows the owner of a landscaping business. He ordered 1 ton of these pebbles, and the truck driver made a mistake and delivered 10 TON! So he has offered to give what he can to me to help me fill my grow beds which is great. I don't know to much about it yet.

As promised here is a pic.

All he can tell me is that they are 20mm pebbles.

Yep price is right they will do

Wish that truck driver would move to Perth and deliver mulch !

Good score Adzza

Yep river stone, thats all I use, you will find your ph will sit around 7.5 with it however

didnt have enough time to attach pics to previous post

What should it be at and is 7.5 a bad thing?

I cannot answer that question becuase aquaponics is new to me as well, for hydroponics I used to keep the ph around 6.5, but I used chemicals to bring the ph down, from what I so far understand most people have problems keeping there ph up, so they add in things like shells to buffer the ph, with river stone your ph will hang around the 7.5, it will slowly come down with the build up of bacteria, but if you wash the bacteria of some of the stones eg to clean or increasegrow bed area your ph will come straight back up

The answer is never really definative.
Lets just say the majority of plants want a PH of about 6 , the majority of fish and bacteria prefer 7.5 ..........
If you system is somewhere in the middle of those figures it shpould be A - OK.

My system spent it's first year with a pH of 7.6 and some of my plants had a hard time with Iron lock out. Need to add more iron to systems with high pH issues unless the source water has lots of iron to spare.

My source water is also high pH so having a system with a somewhat high pH is probably a good idea, otherwise water changes could cause pH swing issues.

After a year of operation, my system pH has come down below 7.6 a bit.

What is the best pH for the situation is gonna be a complex thing since there are many factors involved. Some people run great systems that the pH stays between 6 and 6.5 other people have systems that stay way high. The most important thing (provided the system cycle up and processes the ammonia and nitrite properly) is to keep it stable. I believe many people will tell you that 7 would be the perfect pH anywhere between 6.5 and 7.5 should be able to keep fish and bacteria happy and you should be able to find plants that will grow in that range.