Backyard Aquaponics
A place to discuss aquaponics

gud day,.im dexter from the philippines,. may i ask if what would be the best media for growth beds? would it be the media which has rough surface (crushed rock)?or the one which has the smooth surface?

Assuming the rocks are the same size and composition, crushed rock which is irregular in shape should present the greater surface area for bacteria to grow on.
Harder on the hands and harder to wash though

Yea, technically the rougher rock (more surface area) the better for bacteria growth. Then again, many of us use river pebbles that are relatively smooth and do just fine.

More important about the gravel is that you choose something within a size range that will work for plants as well as for drainage.

Even more important than that, choose a gravel that won't affect the system pH too much. Limestone and marble are generally to be avoided since they will likely keep system pH too high for good plant growth.

oh i see,.im already finished of building the frame for my growth beds,.the next thing to do is to find media for my growth bed,. so what size of the gravel is advisable? im not sure what size would work well for plants as well as for good drainage

Hi Dex. Where are you located? I'm in Silay City. If you are close enough, maybe I can make a visit to see your system. I have a raft system and am building a flood and drain bed. I also have sources of crushed rock and river pebbles but have not decided yet on which one to use. MABUHAY ANG PINOY !

im happy knowing you that your also here,. a pinoy,.im from mangaldan, pangasinan,. Silay City? I guess thats in Negros Occidental,. raft sytem? is that the use of floating material? im still new in aquaponics,. i will also be using flood and drain system,. maybe i will use the bell valve bend over system of siphon,. im also thinking what the best growth bed media for my system,. by the way im planning to rear catfish,.and i will be using framed canvas as my fish tank,.i hope my AP will be sucessful,. i guess i would the first one to engage in AP in our Province and maybe here in Region I,.

Okay Dex. Sayang you're not close enough for an easy visit. But if you have a chance to be near Bacolod, give me a call at 0919-523-5735. If you're thinking of cats, try pangasius hypopthalmus (Viet cats or Dory fish) but they can get really big. I some weighing 8 kgs. I use 15 kgs of tilapia in my system but I do not have enough raft area for them, so, I am building a flood and drain bed adjunct to the existing raft set-up. Keep in touch and let us know how you progress. My email ad: crisgaston@gmail.com

ok sir,.pangasus is one of the newest fishes which BFAR is promoting,.i havent seen yet personally and obcourse eating eat also,.hehehe,. maybe if would i be succesful with my firs AP,.i will try to engage in pangasus,. the reason why i also want catfish because of its marketabilty is no problem,. i guess Aquaponics will be a very promising technology in our country,.we need to start it for it to grow,. we may have problems engaging it right now but everything starts from that,.just like vermicomposting,.its so popular now so different 20 years ago,.

Another issue (problem) with rough rock is that roots grip it better. I have enough trouble shaking smooth gravel free from plants I pull: lava was nearly impossible. (The solution to this if lava is cheapest is to cut off plants and let roots rot). I'm sure even glass marbles would work well. As far as surface area concerns go, don't worry: the area required for bacteria is easily available even on the smoothest media as the beds are so large compared to the fish load. The large bed size is needed for breaking down solids (earthworms help a LOT) and to support enough plants to use the nutrients.

Hum, I thought I replied to this earlier, I must have forgot to submit.

Size. My river rock and washed shells is mostly called 1/2 inch. That means it passed through a screen with squares just over 1/2 inch so contains plenty of stuff smaller than that. I would say a range between 5 mm and 20 mm would be pretty good, and 10-15 mm the best. In the lower layers of my grow beds I have used quite a bit of larger lava rock and put the smaller smoother pebbles over it.

what would be your reason of using quite a larger lava rack in lower layers of your gowth bed? as well as putting the smaller pebbles over it?

For better drainage in the bottom of a deep bed and to take up more space with a light weight rock.

how about mixing them together? would that sill give a good drainage? as well as a good surface area for bacteria?

I don't know about you, but this is a public forum and putting your email address, phone numbers may not be a good idea. Using private message (pm) might be a better idea.

Cheers,

Virgil

I like to have the larger rocks in the bottom since near the surface finer pebbles to hold smaller seeds is better and you are less likely to pull the rough lava rock out of the bed in the plant roots if it is on the bottom of the bed.

Truth is, it doesn't matter that much since over time, things mix a bit but unless the rocks are already mixed before you put them in the grow beds, it is probably easier to was and place the rocks in the beds separately and put the larger rocks on the bottom.