Media

[TCLynx]

For those people setting up new systems, there are just a few things to keep in mind when choosing media.
Primarily, you want media that won't mess with your pH too much. Things like limestone and marble will tend to keep the pH in a system very high due to their calcium carbonate, normally such medias are to be avoided. Shells might not be quite as bad but I still wouldn't recommend them as media, they keep the pH up around 7.6 which is still higher than most plants really like and causes Iron lock out requiring regular additions of Iron to the system.
There are also some medias that have a very low pH tendency, Diotamite or Maidenwell is an example of this. Using such a media will require careful observation and buffering of pH to avoid crashing the bacteria and having terrible ammonia spike.

So before you buy a truck load of the gravel, you might see about getting a small amount to run some pH tests after letting the media soak in water for a while.

FYI pea gravel usually refers to the size of the gravel, not the kind of rock, around here cheap pea gravel is likely to be limestone. Mostly quartz type river pebbles of 1/2" and smaller size are usually a fairly good choice for gravel media. Granite can also be good as can lava rock of appropriate size.
Be sure to wash your gravel before putting it in.

Perlite is generally not recommended as it can be difficult to contain and vermiculite breaks down easily. Of the manufactured hydroponic medias the expanded clay balls of high quality are the only really recommended by many Aquaponics enthusiasts.

Coco Coir, Peat, Sand, wood chips, leaves, and other such medias are generally thought to hold to much water (keep it to wet for the plants) and may also leach undesirable tannins into the water. If trying to use any of these please do it on a small scale in an experimental set up when you can easily take it offline or remove it from the system if something doesn't go right. I once tried wood chips in a small experimental set up and they turned the water so dark that I could not see the fish.

Please add more tips and tricks about media here.

[Wolfenhawke]

Going to try the Coco-coir croutons.  I want to keep the weight (and cost) down.

Here is another source -- though their server is slow : www.greners.com

here is source of more info (seems like an initial rinse is a good idea): http://www.breedbay.co.uk/forums/coconut-coir/6017-new-grow-new-med...

[TCLynx]

Just keep in mind that any organic material used for media will have a limited lifespan before it starts to break down and turn into muck.  If you don't mind replacing the media every so often this might not be that big a deal to you though.  Replacing all the media in a bed will really disrupt the bio-filter of a system so plan to do it in a staggered fashion.

[Michelle Silva]

Coco coir croutons seems good,looked into those a while ago, but had gone with the reg coco coir bricks at the time due mostly to cost. pd $6 a brick (2 cub ft)..croutons seem a bit expensive on a big scale,not sure of price is in bulk or if it's even possible..

I saw pine bark chips used in a hydro demo system at a University research center (water wasn't returned) but used w/ multiple veggies and everything grew well so checking into that now..I was thinking of experimenting with switching out some of the medium in the vertical stacks first. They said that the acidity nature of pine bark wasn't an issue after rinsing.

I read somewhere that pine bark doesn't break down as readily as other organic mulch, so was hoping it would be a couple of years before needing replacement, but don't know how realistic that is.

[Michelle Silva]

and by the way think it is super inexpensive and local for me too.

Michelle Silva said:

Coco coir croutons seems good,looked into those a while ago, but had gone with the reg coco coir bricks at the time due mostly to cost. pd $6 a brick (2 cub ft)..croutons seem a bit expensive on a big scale,not sure of price is in bulk or if it's even possible..

I saw pine bark chips used in a hydro demo system at a University research center (water wasn't returned) but used w/ multiple veggies and everything grew well so checking into that now..I was thinking of experimenting with switching out some of the medium in the vertical stacks first. They said that the acidity nature of pine bark wasn't an issue after rinsing.

I read somewhere that pine bark doesn't break down as readily as other organic mulch, so was hoping it would be a couple of years before needing replacement, but don't know how realistic that is.

[Harold Sukhbir]

Hi Michelle,

I use coconut husk chips for almost six months with little to no breakdown in my AP NFT and now raft. Heres a document to look at

http://ladyslipper.com/coco3.htm

[AJ Grottke]

Reusable media is the way to go; 1 time cost, more sustainable and environmentally friendly, and something like LECA has some wicking ability so seeds can be direct seeded into it.  I always try to eliminate as many non-reusable inputs as possible in soilless growing. I try to limit inputs to fertilizer (fish feed), seeds, H20, and NRG (electricity).

[Dave Donley]

Don't leave out charcoal, has been working OK for me so far, organic, inert, can be homemade, can be grown sustainably...

[Harold Sukhbir]

With the husk, when i harvest, i wash it in water let it dry and spread it in the sun of a few days(destroying the nasties if any) as a precaution and reuse it for new seedlings. Thanks Dave, will do a trial with your suggestion of charcoal next.

Harold Sukhbir said:

Hi Michelle,

I use coconut husk chips for almost six months with little to no breakdown in my AP NFT and now raft. Heres a document to look at

http://ladyslipper.com/coco3.htm

[Harold Sukhbir]

Hi AJ,

Is this LECA the same as hydroton? and is the price range different?

AJ Grottke said:

Reusable media is the way to go; 1 time cost, more sustainable and environmentally friendly, and something like LECA has some wicking ability so seeds can be direct seeded into it.  I always try to eliminate as many non-reusable inputs as possible in soilless growing. I try to limit inputs to fertilizer (fish feed), seeds, H20, and NRG (electricity).

[Dave Donley]

Hi Harold: I joined this forum because Paul Letby discussed charcoal as media, please blame him if it doesn't work well for you!  

[Harold Sukhbir]

Sorry Dave,

I can't blame my friend Paul, so i have no choice but to blame you if it fails.

[Michelle Silva]

We were trying to figure something that could be done on a larger commercial scale..LECA would be cost prohibitive.

AJ Grottke said:

Reusable media is the way to go; 1 time cost, more sustainable and environmentally friendly, and something like LECA has some wicking ability so seeds can be direct seeded into it.  I always try to eliminate as many non-reusable inputs as possible in soilless growing. I try to limit inputs to fertilizer (fish feed), seeds, H20, and NRG (electricity).