Backyard Aquaponics
A place to discuss aquaponics

Joel,

Whats your take on the floating raft system?

Obviously you would need a seperate bio-filter becasue there is no gravel substrate

Hi Steve,

The floating rafts have been very successful for the UVI institute and their system is highly productive.

Personally for myself and the concept of backyard aquaponics I like to try and keep things as simple as possible. Floating raft requires the seperate clarifiers, settling tanks, biofilter, etc. Some means of removing all solids from the water before passing it into the areas where your floating rafts are.

Without filtration suspended sediment gets caught on the roots of the plant, building up, smothering the roots, and slowing or possibly killing the plant. Whichever form of solids removal that you use, the equipment will generally require back flushing to remove the solids from the system and this uses up water as well as removing valuable nutrients from the system.

Where as the gravel grow beds, although they are a bit of a pain because they're heavy, there is no wasted water from regular solids removals and all solids stay in the system, breaking down in the gravel grow beds and adding to the nutrients available for the plants. Generally just a more simple method that makes better use of all available nutrients as far as I'm concerned...... But I could be biased.....

I have a floating gravel bed as a test, however depth of substrate is determined by the wet weight.
I use a polystyrene box or tray, which forms a shallow flat bottomed boat. I punch holes in the botton, and (not required) cover the bottom with a mesh. The mesh has a couple of inches of gravel on top. If you find lighter substrate than gravel, it can be much deeper.
Still is test, but what do you think.?

Interesting idea craysy, I think that should work well, you're getting lots of surface area from the gravel for bacteria to grow on, and you have a convenient floating grow bed.. Though it will be interesting to see how it goes as the plant planted into the growbed start to grow, they may get to big and cause it to be unstable, perhaps you could support it somhow when it gets to this stage.