What the cheapest and best media?

[Kou]

What's the cheapest and best media to use?

I'm planning on having about 8 grow beds, 3'wide 1'deep and 4'wide. From previous year experiment, Hydroton costs way too much. I spend about $140 for just one grow bed.

[TCLynx]

What is Cheapest will vary depending on where you are, but cheapest may or may not work.  If you have a truck and/or trailer you might be able to go to the aggregate yards in your area and pick up river rock or other media fairly cheap.  Just be sure to get some samples and rinse them off and do the vinegar fizz test before you buy a truck load.

Expanded slate and expanded shale might need extra good rinsing and perhaps even an acid rinse to keep them from affecting pH short term.  Log term they seem to be fine.

River rock and granite work but are heavy.

Lava rock works but make sure it wasn't used for any industrial filtering before being re-sold.  Lava rock needs extensive rinsing before being put into a system.

those are all options that will cost less than Hydroton if you can pick it up yourself or find a local stone yard or landscape rock company that can deliver to you with a dump trailer or truck.

[Chip Pilkington]

Hi Kou,

I use river rock in most of my GB's because I like the holding power for larger plants. It's readily available - just need to test it as TC mentioned. You also need strong GB's, as well as the structure to support them.

I'm actually replying because I wanted to share another successful media I use...it's crushed brick. I have 2 GB's running with it right now and they do great. Cabbage, lettuce and tomatoes in the beds now (peas didn't do well). Crushed brick is a bit lighter than rock and comes in several sizes. It holds well, is porous, but without the sharp edges scoria has. It's really inexpensive as well. It a bit more work upfront and that is because it takes 4 or 5 flushes to clear the red color. I just direct the drain away from the tank and run several fills of tap water to clear it. I have never had a discoloration in my system after the 4 or 5 flushes.

One other positive is that it takes direct seeding well. For whatever reason, I have a much higher percentage actually sprouting. My guess is that with the 5/8-3/4 rock, the seeds tumble down too far and the fills continue to work them deeper. The brick is a bit denser, as it's 7/16-1/2 inch or so - I'm thinking the seeds stay put deep near the surface.

The brick should be clean and 100% brick, no mortar or white material as this could affect pH (this could contain lime or who knows what).

Anyway, thought I'd throw another option at you.

[Kou]

I'll try the river rock.  Got to wait till it gets warmer to go.

[Bawlls]

What's the vinegar fizz test? What does this do or show? 
We're in the middle of a media ph test right now. We rinsed & cleaned several buckets full of diff. Media than let it sit in known ph water for a couple of days. Waiting and watching to see how each media affects the PH. We know this is important because recently we filled some beds with regular 3/4" minus like Murray suggests and we have been consantly fighting low ph, well get it buffered up with hydroxide lime. Then the next morning it would drop back down to 6. Very frustrating, when trying to establish a new system.
 Were testing everything from local lava rock, locAl river rock, hydroton, Mexican pebble, hygro mite and more. Even Dolomite,"limestone" which I'm real curious about. It's supposed to hold the water neutral, which seems great cause it seems the water wants to naturally trend down to acidic. Does anyone have experience using Limestone rock either as a media or mixed with their media as a natural buffer?

What's the preffered size media?
I like pea gravel, but have been warned that using to small of media can get locked together with the roots and cause dead zones in the bed. Anyone experience this? 

Angled rock compared to round rock? Any differences, besides ease of removing plants & roots?

TCLynx said:

What is Cheapest will vary depending on where you are, but cheapest may or may not work.  If you have a truck and/or trailer you might be able to go to the aggregate yards in your area and pick up river rock or other media fairly cheap.  Just be sure to get some samples and rinse them off and do the vinegar fizz test before you buy a truck load.

Expanded slate and expanded shale might need extra good rinsing and perhaps even an acid rinse to keep them from affecting pH short term.  Log term they seem to be fine.

River rock and granite work but are heavy.

Lava rock works but make sure it wasn't used for any industrial filtering before being re-sold.  Lava rock needs extensive rinsing before being put into a system.

those are all options that will cost less than Hydroton if you can pick it up yourself or find a local stone yard or landscape rock company that can deliver to you with a dump trailer or truck.

[TCLynx]

There is a fizz test

if you drop limestone in vinegar it will fizz.

Aquaponics will naturally trend downward in pH, however, you don't want limestone as your media since it will keep the pH buffered too high.  Shells will buffer pH to 7.6 and even that is too high long term since it will cause issues with potassium lock out because there will be too much calcium in the water from the shells constantly dissolving.

Bawlls, what is your source water?  If your source water has absolutely no alkalinity or carbonate hardness then your pH will drop rapidly.  You may want to use some potassium bicarbonate and calcium carbonate to get your water buffered up to between 6.5-7.0 before you start blaming the media.

[Bawlls]

I see says the blind man, kinda.So the vinegar fizz test shows...the reaction to acidic water?
I am using filtered RainWater. So it is naturally acidic and soft water. At the Cistern it is 6.5 PH,but by mixing & combing my diff. Filters I can bring it to 7.0 PH at the point of use. I have been trying to buffer up with Hydroxide Lime (Slaked Lime) in the system, not realizing I was actually making my soft water softer. So I should be using calcium carbonate (AgLime) to bring it up instead? Then alter that with  potassium bicarbonate? I have been looking for pottasium hydroxide (KOH) to alter with, but haven't been having much luck even finding it. I got to admit my chemistry knowledge is lacking, but I Want to figure this out, cause rainwater is my water.

TCLynx said:

There is a fizz test

if you drop limestone in vinegar it will fizz.

Aquaponics will naturally trend downward in pH, however, you don't want limestone as your media since it will keep the pH buffered too high.  Shells will buffer pH to 7.6 and even that is too high long term since it will cause issues with potassium lock out because there will be too much calcium in the water from the shells constantly dissolving.

Bawlls, what is your source water?  If your source water has absolutely no alkalinity or carbonate hardness then your pH will drop rapidly.  You may want to use some potassium bicarbonate and calcium carbonate to get your water buffered up to between 6.5-7.0 before you start blaming the media.

[TCLynx]

the slaked lime won't make the water softer.  The calcium hydroxide and potassium hydroxide can be used to adjust alkalinity but they are both fast acting and caustic chemicals and you must be careful when handling them.

The slower acting and longer lasting buffers would be calcium carbonate and potassium bicarbonate and when dealing with rain water you might simply hang a paint strainer bag with some crushed shells or limestone chips in the water to work on buffering your water then you might use potassium bicarbonate in the system alternated with hanging a bag of chicken grit in the system.  Rain water definitely needs some buffering.