I keep running my numbers and I know that they can't be right. So I ask those of you with practical experience...
How much hydroton did it take you to fill a single IBC grow bed?
I know everyone's dimension will be slightly different, but it should be in the same ballpark.
We recommend 325 - 350 liters, Ed.
Most IBC's are labeled with liter and gallon marks. Hydroton is usually sold by the liter. So a 40 liter bag of hydroton should fill up about 40 liters of the IBC. It will depend on how deep you make your grow beds and how deep you intend to fill them as to how much hydroton you need.
If I were making grow beds from an IBC, I'd cut it in half and figure that to fill both of them I need about 1000 liters (if it is a 1000 liter IBC that is.)
SO...it all depends on how deep you want your grow beds to be, Ed. I typically recommend at least 12". No problem going deeper than that but given the expense of Hydroton I wouldn't recommend going much deeper.
You can also use some ph neutral gravel for the bottom 2 inches to save some $
Indeed, if you are going to do a deep grow bed, it is actually quite common for people to use heavier/cheaper gravel for the bottom portion of the grow bed and then the more costly or nicer on the hands stuff on top. This works especially well when the lower layers are heavy gravel and the top layers are a light weight media since the weight will help keep them from mixing up too much when re-planting and stuff. If you go the other way around putting large lava rock in the bottom and heavy gravel on top, there will be more of a tendency to mix since the lava rock tends to be a bit lighter than gravel.
Now if you use gravel for anything, do a little research before you buy a truck load. Make sure you don't buy limestone pea gravel or something like that. Rinse some of the gravel and Do a Fizz test with vinegar with a sample of your proposed gravel. Lots of Fizzing is a BAD sign.
As to figuring out how much media you need with something that might be sold by weight, you will need to find out from the supplier how much of the media it takes to fill a given volume. For instance, the 1/2" brown river rock I use around here is sold by the ton, so how is one to figure out how much to buy? Well I asked the supplier and they told me it takes about 1.25 tons to make a cubic yard of that particular media so then I can go to the conversion calculators and figure out how many gallons or liters I get per cubic foot or cubic yard to help me in the estimation. Lighter weight media will give you more volume per amount of weight. So with the brown river rock I might figure I need 6 tons to fill 600 gallons worth of grow bed (and have some left over for topping up when it settles and so on.) With a light weight media I wouldn't need to buy as many tons to fill that same amount of grow beds.
Hydrotons cost alot from where I am. 40 liters is about $46.00. I will go broke if using it.
You can get something called Viastone (50L Bag) from home depot (on-line only) for around $40 delivered. It is expanded clay rocks, like Hydroton but slightly cheaper. I think it is a bit more buoyant than Hydroton so be prepared to struggle with it heaving if your water level goes higher than 2 inches below the surface of the clay rocks. It is also somewhat rougher so it might provide more surface area for bacteria.
Really??? I can get the Hydroton locally for much cheaper. I guess I'll look into that. It might not be so bad after all.
Again it is not local, they will ship it to you via UPS $29.99 for the bag and around $10 for shipping