Backyard Aquaponics
A place to discuss aquaponics

I use 12-14mm gravel in the bottom 2/3 of my barrels, hydroton in the top 1/3, nice to plant in, and the gravel supports the more mature plants.

I have found out that Pelindaba - the rock on my farm - is a mixture of dolomite and chert. The chert is the hard rock left after the dolomite has washed away. I will be using this so think I should be OK. Don't want to buy in media if possible. I know that my water is hard cos the area I live in is called Kalkheuwel - Lime Hill in old Dutch - very calcium rich water - but my fish are acclimated to it already. Tough little cookies! I don't seem to have excessive algae growth where they are now but that is a drlain-a-bit and top-up set-up for now (actually leak-a-bit and top-up!) so I will have to see in a closed AP system how it goes. I wonder if vermicompost is more acid or more alkali? Is manure not acid?

If memory serves me correctly it is acid... not very, but it is acidic (but it also depends what you put into it!)

Neat! That helps.

If I had to start again ...

a) I wouldnt have to spend so much time stuffing around with autosiphons , now that I can build them to work the first time

b) 2 cartons of beer , 3 mates , 4 shovels and a MUCH bigger buried sump . My current system is about as big as I can push it cause of the sump size

3) Bolt the aeration pump to the top of the tank so it cant slip down and starve the venturi of oxygen , thus starving 18 trout of oxygen ...
That wouldnt happen if I started again

4) pay Joel for a system in the first place , instead of messing around for so long

If I had to start again...
Bury 3 IBC's instead of 2 (I had planned on 4, then got lazy)
Put up lights straight away - so as to be able to work on the system after night fall.

Lights make a big difference to your amount of AP time, thats for sure.

I would cement the sump down so it can not float out of the ground and I would put a timer on the water hose too!

Hi Boris, Couple of questions. What is ratio of size of sump to size of GB's. My 12 beds together will be 4.32 litres without grow-media ( 12 x 500mm deep x 900mm long x 800mm wide). If sump buried how you see if something clogged up? Trying to work out about the venturi being starved of oxygen.... I have no working knowledge yet all just read and learn so far.... venturi is a drain - how it affect the DO for the fish? I need real keep it simple at this stage so beg patience...

Hi AM, What are IBC's?

venturi is on the return side from the GBs to the FT.
a venturi is as simple as a pinhole in a pipe that draws air any time there is flow
IBC is industrial bulk container
holds about 1000ltrs

Hi DDM, Water hose for topping up? You need to top up much in this system?

Hi C, Thanks. Still trying to understand. Why would you put a venturi here? Does a pin hole in a loop siphon from GB to FT constitute a venturi?

Only if it works

I would probably do things more conventional but then it would be less fun, I am going for pumpkins and Killer Tomato's now though, I will put a greenhouse cover over tank next winter, and will add another tank and conventional GB's with standard fish but still keep my experiment tank going with Marron an Pygmy Perch