I'm not sure how you have your beds set up but you could split your grow beds up and try each media. I am not sure about lava rock, but a know people who have grown basil in river rock with great success. They also had a bed with hydroton which did about the same.
With river rock I imagine one of the biggest cons is weight. Hydroton or lava rock would be lighter if you are trying to support the bed. They would also give more surface area to harbor bacteria. Depending on how big your bed is in relation to your 30 gallon tank, this may not be a problem. Where you planning on mixing the media or layering it so you have one on the bottom and one on the top? Best of luck!
Whoohoo! I finally get to gloat about something here (in serbia). 50 litre bag $9.00 USD Liaflor...
Yeah you can mix rocks, hydroton etc...just forget about keeping the hydroton "on top" like some people figure they'll do. After you harvest a couple of times it all gets mixed up.
Ske - I would consider using expanded shale. It's pH neutral and will provide your plants with a little silica. They also have a lot of surface area to allow bacteria to grow as needed. It's also mined here in the United States and not over in Europe. So much less of a carbon footprint.
However, your main concern is to ensure that whatever media you use is pH neutral.
Did you get that pile of chips converted?
Jon Parr said:
...try bio-char. I'm dabbling in that right now, ...
Not yet, Chris, though I'm having a bio-char workshop on December 28th, so I better get cracking
Ske Ske, I don't know if this matters to you...but much of the lava rock sold in the mainland US first did duty as filter material in industrial/wastewater treatment before being sold off to landscaping supply companies and big box stores. I'm not saying 'don't use it', just making you aware of that...
Ske - I've heard that Hydrocorn floats quite a bit more than Hydroton. Can you confirm this for me once your system is running? Thanks!
Ske Ske said:
Thanks for the responses. I have decided to go with a mixture if lava and hydroton. I bought some hydroton online and it was expensive. Nevertheless, it was not enough so I was able to find a local distributor of grow media. There was no hydroton but they are now selling hydrocorn. I have things set up and my next phase is lighting. Going to upload photos of progress soon. Can wait to start growing.
ive heard that the corn floats less than hydroton... they both do better after they soak for a week or two.
Hydroton should really float at all... unless you're flooding too high....
A small percentage will... if tossed into a tank full of water.... but I've never had a "floating" hydroton problem in my grow beds... ever...