Backyard Aquaponics
A place to discuss aquaponics

I saw this picture of a Vietnamese mint plant which got a little out of control posted by Food&Fish



So I thought I would share my fish tank GB tubs which are great for the fast growing plants you want to stop from taking over the GBs.



Basically the tub is suspended over the FT and the changes in water height (tide) due to returning and draining water in a chift pist system make them flood and drain and they seem to work well for my mint wich can be quite invasive.

I can up with the idea while trying to increase GB volume with out having to pump more water from the FT as atm I only have a small sump and could not fill any more external GBs.

Thats an awesome idea Simo!

G'Day Gang,

I have found that the Mints and Goto Kola do well when put in the FT. They don't seem to mind the wet feet.

I will try the Vietnamese mint and see how it goes.

viewtopic.php?f=3&t=6040&st=0&sk=t&sd=a&start=15

The link is piccies of my FT

Cheers
Dennis

I originally had mint and water cress floating too but I wanted to have a cage on top of the FT to stop fish getting out and kids\birds getting in, and I needed to shade the tank to control aglae and temperature. I could have fixed styrofoam rafts to the open areas where to tubs are but I needed the extra grow media to increase the biofiltration. I have both mint and water cress in the tubs because I know they love the wet feet.

That is such a great idea!

Why didn't I think of that? Dang clever.

This way one is actually effectively having two growbeds that flood and drain exactly alternately, without the need for any valves. It will also allow one to shade tanks easily (for trout) and, if the growbeds are fairly small, one can still slide them over or lift them out for better access to fish. You can also use things like half barrels without all the plumbing costs that TCLynx pointed out as being a big drawback.

One issue I see is that the water volume of the system has to be controlled pretty precisely or the flood/drain for the tank plants will vary a lot: perhaps an automatic filler (say a stock tank filler?). Another issue might be feed building up in nooks and crannies and rotting: perhaps having the secondary growbeds in the sump rather than in the fishtank could solve that?

Nice work, mate!

Hi Hydro,

I agree about the water level fluctuation with evaporation and transpiration, If you were trying to grow seedlings you would need to make sure the highest level of the FT tide was always 30mm below the surface of the media and that would mean keeping a close eye on the circulating water volume and replacing the water as it is lost, a float valve would do this.

I have only put more mature deep rooted plants in the FT tubs so far so if it floods to different levels each time the plants still have the bottom of the roots in the water. The way my system floods and drains 90% of the media is constantly damp so i think the bacteria will be thriving and that was the initial aim.

I hadn't tought about rotting materials sitting in the bottom of the tubs before but like you said they are very easy to remove for cleaning out after a harvest.

Thanks for your thoughts.

hydrophilia,

Could not a more controlled affect be that the fill tube for the FT dumps into this smaller GB's then drains right into the FT? If the main system is 15/45min on/off the plants would be fed as well. A small drain hole in the bottom and a slightly larger one on the side to prevent over flooding.

That would be fine if the fill was from a low flow pump or small gravity return, but my sump pump would blast all the GB gravel into the FT, heavier gravel might be OK too.

Simo put a tee piece with a tap back to your sump or fish tank
I have a 15 mm running full bore back to the sump
I run my 28.000 litre pump 3 min every 1/2 hr no problem [ been running 2 years now]

Sorry: "fill tube for the FT"? Is this the return from the growbed to fishtank or from sump to fishtank? Either way, with the standard 15:45 one is likely to have a situation where all the growbeds are concurrently full of water, requiring more total water volume in the system.

The options for filling multiple growbeds are
>concurrently (all fill at same time: uses maximum water but is simple),
>consecutively (no more than some fraction of the growbeds (2/3, 1/2, 1/10) is filled at one time. It takes a "spider valve" or some other clever thing, but can work and let's one get away with smaller or no sump)
>randomly (an example is a bunch of growbeds with a continuous flow and autosiphons. Any fraction may be full at any time, so it has same requirements as concurrent filling).

The beauty of his idea is that it is perfectly (but simply) consecutive: the growbeds are never, ever concurrently full and there is no need for any valves or timing or other things to go wrong (other than maintaining water levels).

hydrophilia,

If its the return water going back to the FT, but takes a detour thru the containment beds first I don't think it would matter would it?

What a great idea. I currently have small papyrus suspended in my fish tanks to give the newly hatched baby fish a place to hide. I had never considered using the same process for my actual food plants.
Now I am heading to Bunnings to get some more of the hooks I used.
Thanks.

If more growbeds are full at once it will affect the water level (in sump or fish tank) more.

I cleaned the mint one out today to replace it with Vietnamese mint, just look at this root mass and imagine how much damage it could have done in a full size GB.