Backyard Aquaponics
A place to discuss aquaponics

just saw this thread. I believe the depth of the grow beds also allows for mineralization of solid wastes over time without causing blockages. To me thats the main issue.

That is a good idea, but my hydroponics tank has an 8 inch opening and is about 6 long.

Mineralization of solid wastes over time? That sounds like a future problem if to keeps building up. What's the longest time an aquaponics system like this these have run?

I bet you could figure out a way to do it, if ofcourse you are convinced that the tank would other wise make a good fish tank.

I was thinking of spraying the outside of plastic beds to prevent light from bothering the bacteria. If that was the reason for having deep grow beds.



That makes sense. I have always re-circulated my nutrients for 30 to 60 days. So, the setup is in place. I would just have a bugger of a time getting the fish out

If you were to perhaps flood to the top of the beds, or water from the top... flush your existing system with water for a few days.... and dump it to the garden

then I think you'd probably be right.... maybe let it dry a day or two in the sun to see if any salts crystalise out onto the surface then flood again.

Most people haven't bothered to spray the outside of their beds but there's no problem doing so.... as long as the material used is non toxic and want leach.... remember it will be exposed to ammonia laden water for periods of time.... being slightly acidic this will exacerbate any leaching effect.

Would a shallow bed with a good population of worms be as effective for mineralisation as a deep bed? a kind of an active system versus a passive one
It would certainly be more economical to make a shallow bed, comparitively lightweight and more planting area for a given amount of gravel or pricey hydroton.

The main issue would be keeping the temperature stable, although i can`t help but think both shallow and deep beds would hover pretty much around the tank water temperature with a constant flood and drain.

Lightproofing is less of a problem once the vegetation starts shading the gravel, perhaps using a smaller sized media would help too.
Providing support for tall plants could be solved by using a trellis system.

I have drowned to many worm to even try to have them in a aquaponics grow bed. lol Worms have just never worked for me.

I think joels have run for 3 years with out clean out.

I think the ideal is to have enough volume / depth to allow enough time to mineralize before blocking

Regarding the light sensitivity of bacteria, it is more of a problem in initial cycling , once the have colonised a surface they are more tolerant of light, and as mentioned plant growth will shade and even an inch down it will be dark. Nitrifying bacteria even colonise limestone building walls, thriving on the high ph and nitrogen from acid rain.

I did this to clear plastic containers on my original setup - had no problems with bacteria growing or algae forming
Black plastic stuck over sides

Two top left containers are the GBs with the plants growing quite well

Those are some healthy looking plants there Ell!

That would work. Black would be hot on a 100 F (37.8 C) day though. I guess I could wrap with that silver colored tarp, or like I did before glue some aluminum foil to the outside..

There is always Panda. Good thing is you can reverse it in winter to get some heat into the system

Thanks for all the input. I will go ahead and try to get 12" GBs. I calculated what concrete would cost and I think I may just build my grow beds out of concrete. My wood beds are pretty, but the lumber we get is so green and from new tree growth so its bendy and crackie and well sorry. Concrete would be cheap and I could make it any shape I want.

I found this:


Perhaps this is the real reason to have deep grow beds. It makes it harder for oxygen to get down to the bottom, thus keeping more bacteria active.

So that begs this question. What about a bio filter AFTER the grow beds. A filter that stays full of water and there for always anaerobic, but being after the grow bed would not steal any nutrients from the plants. Ofcourse, that could mean more bacteria that convert nitrate to a gas.. The grow beds are always being refilled with air when they drain.

What do you think?

the growbeds -are- a biofilter. What is the differentiation you are making between a biofilter and a grwbed?

Regardless, since these are recirculating systems, I don't think order matters except for solids handling.