Day 8: Growing Raft

The most common commercial growing system for aquaponics is the raft method.  So, of course, it would be silly for me not to give it a go.

The only major problem I have with this method is that the current 'norm' for this process is using rockwool as the growing media for each plant 'pod' in the raft.  Rockwoll is made by heating rocks such as basalt and chalk and actually making a wool-like mat.  I'm concerned about the way these rocks are mined, and about the sustainability of such a product.  Also, I have read that rockwool can pose a problem in that it must be pH buffered before use.  Again, this usually requires chemicals.  Eventually, I intend to look into coir (recycled coconut husks) for this instead of the rockwool.  But, for now, I don't have any coir so I am using plain old polyester fiber fill.

 

I actually find this to be a great inexpensive filter media (though I realize it's probably not the most sustainable material that ever existed, either).

The raft itself is simply a piece of styrofoam cut to fit the water chamber with circular holes cut in it for each plant.  These styrofoam rafts should be able to be reused for years to come.   

The plants were transfered to the raft on day 8.  About 3 of the plants shriveled and died.  I later determined this was because the roots did not reach the flowing water below.  The polyester fiber fill does a great job of holding the plants in place, but there is not enough in each cell to really be able to wick much moisture up to the plant.  By 14 days, I found the root systems were much larger and far more viable for transfer to the rafts.