Backyard Aquaponics
A place to discuss aquaponics

Hi, I have been a long time guest, but this is my first time to post.

I currently have a small 25,000L RAS which has been functioning for 3 years now. It was constructed from large plastic tanks and has served well, and now we would like to scale it up.

I would like to add another 50,000 L of tanks plus grow beds/filters.

The tanks will all be 1.5 meters tall and I am considering cement block and plaster for the walls.

If you were building these tanks how would you do it?
- what would you do for a slab?
- how would you connect that slab to the walls
- what would be your major concerns?

I appreciate it

Blake




Sent from my iPhone using Tapatalk

Welcome to the forum Blake

Thank you very much.

Hi Blake
Bear in mind that this a backyard site.
Free advice can be worth what you pay for it.
As I understand it the PH of the water can be affected by the cement construction.
Earthan ponds with liners is another consideration.
Temperature fluctuations would be modified by sinking the ponds into the ground.
Round ponds.No question.
Central bottom drainage. Consider the Cornell system.
Talk to the local swimming pool constructers.

_________________
Titus
----------------------------------------------
My system: viewtopic.php?f=1&t=21619

My Blog: http://titusfishcake.blogspot.co.uk

I'd recommend talking to swimming pool makers as well. I've made a concrete pond, and I'd make a ferrocrete pond all the way around, but I'd never made it for that size, and I'm guessing the pressure against the walls of tank that big would be considerable, and I don't know how thick it'd need to be.

For something that size, I'd go with the experts.

_________________
My System

My Aquaponic Youtube Channel

The Black-Byron Ice Creamery Youtube Channel

Without knowing what the ground conditions are in your area?

You will need at least a 24' x 24' concrete slab, that will support 300 lbs a sq/ft live load.

I would use a 6" depth with #6 rebar 12" o.c.e.w.

The inside of the tank is 22' 4" diameter.

Once the concrete is able to walk on find the center and scribe the diameter.

After a few days of curing, scribe the diameter of the tank in the fresh concrete.

Using 8-8-16 Concrete blocks, lay them end to end around the outside of the circle.

Using a Drift pin, mark the center of each hole in the fresh concrete.

Remove, and set aside the CMU's and drill a 1/2" x 5" deep holes in each Drift pin hole.

Cut #4 rebar x 5' long, and pound them into each hole.

Then replace the set aside blocks.

Pour the cells with 4' of concrete. This will keep them from moving later.

Using a masonry saw, cut 2 slots 1" deep x 1 1/2" apart in the center walls of each block, and knock out the concrete between the cuts.

Next take a #4 rebar and lay it into the slots the entire wall with 16" min, laps.

Repeat the process of cutting slots in blocks and stacking them, filling the cells with concrete as you stack and adding the #4 rebar.

After stacking 8 blocks high you will be a 61" ( 1.55 m )

After all the blocks have been fill, plaster the inside and outside.

Note: I don't know the metric sizes of your materials, if I did then I would adjust the inside diameter of the tank to what the CMU blocks are, At 1.55 m high you should have a min, of 6" of clearance from the top of the wall to the top of the water.

Without knowing what the ground conditions are in your area?

You will need at least a 24' x 24' concrete slab, that will support 300 lbs a sq/ft live load.

I would use a 6" depth with #6 rebar 12" o.c.e.w.

The inside of the tank is 22' 4" diameter.

Once the concrete is able to walk on find the center and scribe the diameter.

After a few days of curing, scribe the diameter of the tank in the fresh concrete.

Using 8-8-16 Concrete blocks, lay them end to end around the outside of the circle.

Using a Drift pin, mark the center of each hole in the fresh concrete.

Remove, and set aside the CMU's and drill a 1/2" x 5" deep holes in each Drift pin hole.

Cut #4 rebar x 5' long, and pound them into each hole.

Then replace the set aside blocks.

Pour the cells with 4' of concrete. This will keep them from moving later.

Using a masonry saw, cut 2 slots 1" deep x 1 1/2" apart in the center walls of each block, and knock out the concrete between the cuts.

Next take a #4 rebar and lay it into the slots the entire wall with 16" min, laps.

Repeat the process of cutting slots in blocks and stacking them, filling the cells with concrete as you stack and adding the #4 rebar.

After stacking 8 blocks high you will be a 61" ( 1.55 m )

After all the blocks have been fill, plaster the inside and outside.

Note: I don't know the metric sizes of your materials, if I did then I would adjust the inside diameter of the tank to what the CMU blocks are, At 1.55 m high you should have a min, of 6" of clearance from the top of the wall to the top of the water.

Thank you everyone for your input.

We are located in a rural part of Rwanda, on the border with DRCongo. This is a very volcanic location, and after one digs down through about 1 meter of decomposed volcanic rock/soil you encounter solid volcanic rock. We have actually excavated a 15m x 15m pit for the first version of the project and we will be using the remainder of the pit for this project. Our tanks will be supported on 3 sides by the rock walls of that pit.

I have decided to use a 15cm reinforced slab as Old Prospector recommended, the full length of the fish tanks. Then i will build my walls on top of that. Instead of building walls with the long side of the block facing the water, i have decided to turn the block 90 degrees and use what would normally be the side of the block as the face. This will effectively give me a wall which is double thick providing both increased density and increased dead weight.

As i continue to process the details of this project, i am now looking at what material to use as bio-filter medium. As we are located in a rural part of Africa, HDPE bioballs or K medium is not an option (nor is it sustainable for us). Also, as we are talking about a large scale project, it would be ridiculously expensive Initially i was considering 2-3 inch lava rock (as we have TONS of it) in small mesh bags to facilitate removal and cleaning.

What is the current thought about lava rock? Are the bags a good idea or is that a waste of time and money? Do you have any other ideas to help with cleaning the dead crap off of several tons of lava rock? Would you use a top down or bottom up method with lava rock?

I saw a guy on this forum using bottle caps, but we do not have a good, bulk supply of that.

I have also considered balls of loosely wound twine.

What ideas do you all have on this subject, keeping in mind that this will all be taking place in cement tanks at a depth of 2 meters (in the case of the bio filter)?

Hi Blake
Couple of back of cigarette packet ideas.
Polystyrene beads in bags.
Plastic bags tied into as many knots as you can.
Plastic Rawl plugs.
Cut up plastic electrical conduit

_________________
Titus
----------------------------------------------
My system: viewtopic.php?f=1&t=21619

My Blog: http://titusfishcake.blogspot.co.uk

Hi Titus,

Thank you for these ideas.

One idea which came into my head today was to use plastic bottle caps.

I have modified my fish tank plan so that it is now 40.5m3 divided into 3 equally sized tanks. After the solids filter, I plan to have a 8m3 bio filter. I am considering dividing that in half. The first half would be a moving bed filter filled with the plastic caps mentioned above, which would then flow into the second half which could be filled with the small lava rock in mesh bags.

What do you think about that idea? Comparing the various options above, what do you think?

Thanks again for the ideas, I am going to need to process through thoes