Backyard Aquaponics
A place to discuss aquaponics

Hi,
Going to do a gravity system with no sump tank.
Hole is mostly grey clay and rock at the base.
Sides seem quite firm.
Can anyone recommend a base for the fish tank I am going to put in the hole?
I'm thinking blue-metal or smaller road base.
(tank is galvanised corrugated iron)

You going to dig in the 22000L tank?!?

Just quietly, NO.
Especially if you'd seen the boulders that came out of this hole!

wow! Impact crater!

Uncle Yarra - I just noticed the hill behind the tank site
You may have thought of this but...
Will you put an earthen water diverter at the top of the cutting or allow the run off to flow down the cutting?
It looks like you get a bit of rain.
NOI
C1

Sorry creative1,
A bit of a running joke with gemmell & myself about an old tank of mine.
No, the FT's will be 1.8m diameter, 1.2m tall, sunk 850mm into the ground in a shed not shown in that picture.
As you can see, the hole pictured is now somewhat occupied by the main water tank for the house...

even more reason!

creative1,
The tank is all back-filled now and hasn't presented any problems after heavy rains (bit hard to tell from the picture, I know).
others,
Any dramas using blue-metal as a base? Is paving sand better perhaps?

I'd use some type of bedding sand - mainly because that is what is normally recommended by manufacturers on installation I believe...blue metal has sharp edges and may penetrate the base at some later date

Crusher dust is great. Packs down tight and flat. I have it as the base for my greenhouse. Think I used a metre in a 7 by 5m gh. If you used that in say 4 by 1.5, it will give you a ripper solid base 10-15cm deep.

yep, crusher dust is what you want.
But a tank in a hole can float out, especially if the sides are clay. Any water that runs into the hole will pool in there. If you fill the hole in the water table can rise anyway. If the tank is at all empty it will pop out. Have you thought about one of:
-drainage pipes or leaving one side of the hole exposed
-bilge pump in the cavity
-concrete the tank into the hole

steem,
All but the last idea (concreting), which is a good one.
tt,
I was concerned about crusher dust as the guy who put in the in-ground tank wouldn't build a tank on top of anything but blue metal. sure a concrete tank is markedly different to a C.I. one, but his point was that the crusher dust turned slushy once it got wet and could cause undue settlement of the tank.

All you need is a good down pour of rain and the sand will be washed out from under the tank, and it might move... I would make a concrete pad to sit it on...

Got pictures now.
Gal sides will be laserlite.

Don't follow you Yarra??