Backyard Aquaponics
A place to discuss aquaponics

Very true!

Also 'cause a friend (also female) will be house-sitting for me soon .. thought it would be pushing the friendship a bit to say .. 'can you feed the dog, cat, chooks, ducks .. oh and you see tank over there . can you just ....'

As for me, my first system was built to learn from so I will definitely be making changes. Some of them will be:

Use a combination of different gravels in my growbeds

Simon[/quote]

I was wondering why the different sizes. I am starting to put my first system together and reading this thread with great interest

Chelle

It's most likely that he means various types of gravel not sizes.
Probably to get the benefit of all sorts of minerals so there are fewer, if any, deficiencies in plant growth. (It's my guess).

Oh.... pity. I have gravel (lPelindaba rock which I think is dolomite) on my farm that is not all exact in size. I am sifting topsoil for a field I want to establish later cos too many rocks. The resulting gravel from sifting ranges from pea size to about double that. Would that be unsuitable? Chelle

Doesn't have to be a uniform size Chelle.... as long as it's not too small, as it will settle with the flood and drain action...

Just make sure it's not so small that it could clog your siphons...

Will dolomite drastically change the ph levels? I drove a spreading truck for a while on farms and have spread dolomite on paddocks but can't remember why

Oh found it, dolomite is used for raising the pH of acid soils and preventing calcium and magnesium deficiency

&

Dolomite (pronounced /ˈdɒləmaɪt/) is the name of a sedimentary carbonate rock and a mineral, both composed of calcium magnesium carbonate CaMg(CO3)2 found in crystals.

&

In horticulture, dolomite and dolomitic limestone are added to soils and soilless potting mixes to lower their acidity ("sweeten" them). Home and container gardening are common examples of this use.

You may not want to use dolomite as your grow bed media as it will definitely cause some pH issues. A little bit might be a good thing for buffering but a whole grow bed of it would probably not be easy to deal with. So you should keep a few bags of it on hand to place as needed for buffering but I would go burying lots of it in the beds where you can't easily get it out.

I have used tons of shells mixed with gravel for media and I'm having enough pH trouble with the shells that buffer to a pH of 7.6.

You are spot on gokul.

I have a theory that, as I am adding minerals to cater for signs of deficiencies, maybe that will be overcome by having different types of gravel in the system as each one will (potentially) leach trace amounts of different minerals.

Just a theory, but one that makes a certain sense to me.

Simon

I have dolomite beds, no ph probs in 2 years, with shellgrit added as well ph is solid at just over 7.

Hey gnash, one post says raise ph, another says lower...could be correct, aka buffer

Expanded clay ballsare much easieron the handsbut more expensiveper cubic meter than gravel,,,perhaps the planting areadone with ECBalls may be worth the extra $ for some people.

DANG space-bar ,,,RRR

bit early Chappo

Shift work,,what's early morning for some is my evening:)

Space-bar isstillapain.