Backyard Aquaponics
A place to discuss aquaponics

So I've finally started work on my new system.

This will be the third system I have made and by far the most complex.

It is going to be a CHIFT PIST system comprising of 1 x 1000L fish tank made from a food safe IBC, 1 x 600L sump tank made from a food safe IBC and 2 x 130L grow beds made from food safe dog baths. I hope to be able to add another 4-6 grow beds without adding more sump tanks in the future.

The plan is for the main fish tank and the sump tank to go inside a garage so that they are out of sight (need to keep the system looking neat!) and easier to keep a bit warmer in the UK winter and for the grow beds to go outside along the south facing garage wall.

Here is the garage before being tided up...



And after...



IBC's in position waiting to be cut...



Outside south facing wall where the GB's will be...



Dog bath GB...



I had to go and rescue some goldfish so I set one of the dog baths up as a temporary home for them...

I'm going to be using a SLO in the main tank but 90mm fittings are hard to find in the UK so I've gone for 110mm instead.

I thought bigger would be better than smaller. Can anyone confirm that 110mm will be OK?

Picked up some 110mm tank connectors, some 40mm tank connectors (for growbed overflow) and a few 12" air stones.

Big is fine. allows for expansion.

Great. That's what I wanted to hear

Have you drawn a sketch of your system? In particular, what are the relative heights going to be between your FT, GB(s) and ST? From the photos, it might be possible to do away with the need for a ST?

Also, 110mm will be fine as a SLO so long as you have a large enough pump to keep the speed of the water flow through the pipe high enough to keep solid wastes in suspension, however, initially, with just 2 small GBs you'll be hammering massive volumes of water through the media, and you're going to have size your drains accordingly (which is going to take up a lot of space in a small GB). You might find you need to start with more GBs to keep the water flow through each GB "reasonable", or have a smaller SLO and smaller pump and upsize these when you add more GBs later. These sorts of details will become very apparent in your system design sketches.

Plan three times. Measure twice. Cut once.

Here is a badly drawn plan of the system...





The height of the grow beds will be dictated by the level that the SLO comes through the wall. The floor levels are different (lower on the grow bed side I think).

I did think that I could reduce the size of the vertical section of the SLO by putting a smaller (40mm?) pipe inside with the end sealed which would reduce the internal volume of the SLO.

Been shopping and I now have a bunch of pipe and fittings for the plumbing...

How exciting
Black looks cool!

Cleaned up the pump that came with the rescued fish. Its an Aquaforce 2500.

6mm solids handling
Maximum flow rate 2500 Litres / hour
Maximum flow rate @ 1m high = 1750 Litres / hour
Maximum flow rate @ 2m high = 875 Litres / hour

Does that sound like it will be good enough to start with?

Lets say you have zero head loss, pumping from the ST to the FT (there will be a slight loss, but let's just work with this for a while, as worst case) :

Q = Your pump is pumping 2500L/h or 0.6944L/s = 0.0006944m3/s
A = The area of the 110mm SLO is pi * 0.055 * 0.055 = 0.003025pi ~ 0.0095m2 (this could be more or less depending on how your pipe standards work?!)
v = the velocity of water in the SLO = Q/A = 0.073m/s or 7.3cm/s
(Always check my maths, just in case!)

This flow is quite slow so the SLO may have difficulty in collecting and transporting heavier/denser solids i.e. it's not going to be very efficient, or at least it's not going to be as effective as it could be.

HOWEVER...

You're still going to be dumping about 2500L per hour into 2 x 130L GBs. When these GBs are filled with media which fills, say 60% of the volume (you only require 40% of the total volume of water to fill the spaces between the media) then :

260L x 40% = 104L of water required to flood both beds, which will take less than 150 seconds with your pump!

In order for the bacteria on the media to do their work and process the ammonia and nitrites, they need to be on contact with the water for (according to some papers) 10-15 minutes, and the flow of water through the media should be sedate and leisurely for the media to be able to filter solids from the flow. If you're blasting water through, all you're doing is pressure cleaning the media!

If you reduce the diameter of the SLO (you only need reduce the size of the "pickup" or the vertical section) then you'll increase the speed of the flow and this will be better able to vertically transport solid waste, and if you also redirect some of the excess flow ST -> ST to provide aeration of water which will eventually be pumped through the FT, you'll be able to increase the contact time of the water in the GB and slow the water flow through the media.

Of course, you could also add more GBs now, which is going to be inevitable in the long run.

Plan three times, measure twice, cut once!

Thanks bunson. Some great maths there

Looks like I should reduce the size of the SLO pick up and divert some of the water back to the sump to start off with. I do intend on adding more grow beds but this wont be for a few months at least.

I plan to set the grow beds up as constant flood with a 40mm overflow and a few small holes in the bottom to allow water to drain then run the pump on a 15/15 min on/off cycle.

You think that sounds OK?

With 260L of filtration available in an immature system, I'd not be adding any more than 10 fish to the system (absolute max). 10 fish in ~1000L of water should be able to "survive" a longer pump-off period which will save you some money; a tried and tested timing is 15/45 minutes on/off, with additional air, even with prima donna fish such as trout.

If you divert half the pump flow back into the ST (or just use a smaller pump) then you'll be delivering about 1250L/h to the FT and GBs, which means the GBs will flood in about 5 minutes and remain flooded and more sedately flowing for the remainder of the pump cycle 10 mins, then drain down slowly over the pump off cycle (if you initially drill one 4mm hole in the standpipe, this should suffice in this instance? Some testing may be required). With only 1250L/h arriving in the FT, if you make the vertical section of your SLO from 50mm then you'll achieve a flow speed of about 17cm/s which is pretty good and should be able to transport all but the densest objects/waste, or about 27cm/s for 40mm pipe (this restricted flow will mean a higher "tide" in the FT as the head pressure builds to its max, but it's certainly achievable)

This is timed flood and drain. Constant flow would be if you didn't cycle the pump on/off, constantly flooded if you didn't have slow drain holes in the standpipe.

Prefect.

I plan to stock with 10 European Perch to start with so that sounds about right. I also have a small bio filter that I could run the excess pump flow through before it returns to the sump if that would have any advantage.


I'll reduce the vertical section of the SLO to 50mm as suggested and see how things run. I guess that I can keep the outlet at 110mm for future expansion.

Thanks bunson, you have explained it very well

Picked up a new air pump today for the temporary tank that the gold fish are in.

http://www.hozelock.com/aquatics/pumps/ ... -1805.html

Hopefully it will be useful in the main tank once the goldfish are in there.

Started cutting the IBC's today.

Marked the top of the FT...


Top of FT cut...


I placed the FT on some concrete blocks to lift it a little higher...


Removed a cross bar and marked the hole for the 110mm SLO outlet...


SLO connector hole cut. Not the neatest but it's good enough. I used a dremel with a speed cutter bit to cut the IBC...


SLO tank connector installed with a bit of silicone. I also put the top cage bars back in place to help keep things square and placed the tank in its final position with a 150mm gap between the tank and the walls so that I can add some insulation when the Great British winter draws near...


Tomorrow, I'll cut the sump tank and maybe drill 2 huge holes through the wall so I can start on the outside grow beds.