Backyard Aquaponics
A place to discuss aquaponics

So, if one GB requires 11cm of tank water, two will take 22cm. This is about 22/66 or 1/3 of your FT water and that is normal.


Well, either you have fish that don't mind the change or you modify your setup. As Rupert pointed out, a sump allows a CHIFT PIST system, something I have been very happy with for two systems I have running.


Some use much less medium...

I have a swimming pool (about 30k liters) running through a growbed with a volume of 8000 liters. The entire volume runs through about once per day. I only have about 20 trout in there, about .5kg each, anad they are healthy, so far.

I also have a 3500 liter fish tank with an 1800liter growbed and roughly 50 trout (20kg?). The growbed floods and drains about 4x per hour, so is near the water turnover of 1x per hour.

As I figure it, one could have a fishtank with volume V, a growbed with volume 2V, and a sump of any size, so why can't one combine the sump and fishtank and gain some safety in case of power outage? I realize there are some issues:
1) the water does not move as fast, so fish waste is not swirled and collected as well,
2) It can be much harder to catch the fish,
3) a larger tank is harder to shade,
4) if the fish are less crowded they tend to lose food more easily (which then rots or is eaten by worms), and
5) there may be issues about ammonia circulation (but I am not convinced and have not run numbers).

I would re-iterate the question about "was there media in the grow bed when you flooded it?"
This will make a big difference.

If you have say 500 liters of fish tank and a total of 500 liters of grow bed. When you add media to the grow bed, you should be able to flood the bed and still have at least half of the volume left in the fish tank. Provided the fish tank is deep enough and you don't over stock, you should still be ok. (A really big shallow fish tank might leave things too shallow for the fish but most fish tanks are deep enough for this.)

If you want a system with twice as much grow bed as fish tank, then you need to have some method to deal with the water fluctuations. The primary way has been to have a sump tank but now there are these fun indexing valves that can flood grow beds in sequence which could make it easy to have a 2:1 system without a sump tank.

As to fish. I think catfish are a wonderful choice!

Hello,

i've gravel in the beds when i tested.
I think about a second pump, one pump for each bed.
So i can timer the interval per pump and it leave only 11cm per flood not 22cm.

My actually problem is:
I use a 1" hose for the loop siphon.
My pump makes 1700L/h. Where must the loop be?
At the moment the loop is directly behind the bed, and then the hose goes through the greenhouse to the fishtank.
Do you mean, when i connect a 2" hose with adapters to the 1" fitting in the growbed, that it'll suck more water, without replacing the expensive fitting ?

Dom

I'ld like to give you an update.
Here are my tomatoes.
When i gave them 5L of readings 0/0/100 they need only two days to remove any kind of nitrates

Dom

Healthy tomatoes.