Backyard Aquaponics
A place to discuss aquaponics

Still very much in design phase at present. After running some models in sketchup and working out that my original location did not get eneough winter sun using the shadow calculator I deciced on this location:



GBs in the front garden and FT in the back under the house's southern eaves (almost full shade all year). The block slopes down from the GBs to the FT about 0.5m, so I may need to dig the FT in a bit and raise the GBs.

I need more clarity however on GB to FT ratio and system design. At present the design is this:



With 1000L of GB media and 1400L of FT (across two IBC FTs) (I've allowed for space at the top - baths won't be totally full with media). My questions are:

1) how much allowance is normally put into a CF system for pump failure? In this system a pump failure would drain approx 350L of water from the GBs (assuming 1/3 GB volume is water) into the fishtank causing overflow. Is this failure mode normally taken account in system design, i.e. the system is designed so it will not overflow if a pump fails?

2) If I were to run this as flood and drain, would I need more FT volume? this FT system (2 IBCs) would go
from 1400L full to about 1050L with all the water in the GBs. This is neglecting water volume in the pipes, which I'm assuming would not be that much. Is a reduction in volume of 75% OK for the fish (Prob SP to start with)

3) What diamter pipes do people generally use for the water supply to the GBs and the drain back to the FTs? Is 40mm overkill?

4) Is there a problem with having the FT 13m away from the GB? I've done this so the FTs are in hte back garden and more protected from people wondering in tothe front garden.

5) Are leaves from trees such as eucalyptus a problem if they fall on the GB? Would this be eneough to cause toxicity to fish?

Thanks in advance, appreciate any feedback/comments on the design.

Cheers
Matt

40mm pipes is definitely not overkill when you are pumping 13m. While friction in pipes can be discounted for small systems, a 13m distance is significant IMO. Read my post here for the link to the calculator to work out your pressure loss.

What is the vertical height that the growbeds are above the fish tanks? You will need this to calculate the pressure drop ("head"), in order to select the right pump. You probably only need one 40mm pipe from the FT, and change to 25mm just before the beds. If you want to put valves on each GB, the 25mm valves are much easier to turn and are much cheaper then 40mm valves.

With the drain back to the FTs, remember that the water is moving entirely by gravity, so will move slower than pumped water (unless you have a very high fall). You could use 40mm pipe if you give each GB its own drain pipe, or you may want to simplify it by using fewer 90mm drains.

I have eucalyptus leaves fall on my GB. I just make sure I check the beds regularly and clean them off (including under the pipework and plants).

There is no problem with the pipes, as long is you make sure that nobody can break or damage them. Some people bury their pipework, but that does have the disadvantage in F&D systems that water is left in the line after pumping.

thanks for the info. I'll get a level line in place and get an accurate figure for the fall, then I'll start looking at pumps etc...

Just had another thought while I'm in the the planning stage...

Is shade cloth essential for growing plants in a Perth summer?

I originally thought that it may not be due to plenty of water being available to the plants, though where I'll be locating the system will get a full days worth of sun in the summer months. Will this still lead to scorching/bolting due to high temps?
Thanks
Matt

ps plan to grow leafy greens/ toms/ cucumber/bush beans in summer

My two systems cope with full sun in Perth with no problems (and strong easterly winds). I do try and keep plants covering the media over summer - I assume the sun would heat the media faster if it could shine directly onto the expanded clay.

Looks like I lost some posts in thr forum change. To summarise I decided to go to a BYAP GB as it is equiv to 3.5 baths of growing area and takes half the media of 3.5 baths so that its cheaper. And have you ever tried plumbing half a bath

Anyway, system design now looks like this:



I think its a combination of a basic F&D and CHIFT PIST. Any comments would be wlcome. Does anyone foresee probs with pumping from the sump directly to the two IBC GBs, while pumping the remaining water to the FT to SLO out of the FT to the main GB. I could also feed the IBC GB (on the ST) this way.

What Could I keep in the ST - would a varying water level of 40cm to 80cm be too much to keep fish such as silvers or redfin? Would that only be suitable for yabbies/marron?

And how much 'fall' is reccomended for gravity fed pipes?

bumpaRama. Anyone? Should i be posting questions on my system somewhere else on the forum? Thanks Matt

So, you're pumping from the sump to both grow beds AND the fish tank?

Sounds like at CHOP 2 setup except for the SLO into the GB instead of the sump. I can't picture that in my head.

Is there any reason you're not doing ST -> GB -> FT -> ST via SLO? I don't have any experience with it, but I'd imagine you'd rather have your solids in your sump tank rather than your grow bed... The solids will eventually clog your media and you'll have to clean it out (so the story goes).

Someone with more experience could tell you if having solids in your GB is beneficial somehow.

In any case, I'd think you'd want to always drain your grow beds into your fish tank since that's the cleanest the water will ever be.

If you're going with roughly horizontal pipes, the slope required to move the water depends on the volume of water and the length (and possibly diameter) of the pipe. A trickle is going to need a very steep slope and as the pipe gets longer, friction will reduce the momentum of the water. A large volume of water isn't going to need much of a slope at all since the friction will be (mostly) removed by the film of water at the edges. With smaller pipes, this benefit is reduced since the percentage of water in contact with the pipe walls is higher.

So the short answer is "there are too many variables to give you an answer" If you have a decent amount of flow, I'd think 10-15 cm would give you some really good flow, and might be overkill.

As I read this over, it isn't clear... The part that starts with "If you're going with roughly horizontal pipes..." is answering the 'And how much 'fall' is reccomended for gravity fed pipes?' question

You want solids in the GB where they will be filtered out by the media, then break down to release their micro-nutrients through the mineralisation (or mineralization) process. You really don't want solids a) in the FT with the fish where they wont break down into beneficial nutrients, but into harmful toxins, or b) in the ST with the pump. I wouldn't be pumping from the ST -> GB either, but pumping all water from the ST -> FT -> GB (via SLO) -> ST

Any fall will be sufficient, so long as the diameter of the piping is commensurate. I'd be pumping using a 25mm discharge from the pump to the FT, a (minimum) 50mm SLO to deliver water to a 90mm distribution manifold which delivers equal volumetric flow to each GB through 25mm risers, then a 32mm or 40mm drain (depends on if you're working CF or timed F&D, siphons etc) back to the ST (or into a 90mm common drain, if required).

The drains are really the only issue when it comes to relative heights, especially if you're going to fiddle with siphons; with the obvious exception that the GBs have to be positioned below the height of the SLO in the FT of course!

If you've got a natural slope to exploit, I'd be positioning the FT at the highest point and the ST at the lowest point and the GBs in-between.


$0.02

thanks for the reply - Didn't want to put the FT at the highest point as that would put it by the verge and we don't have a fence - just a bit worried about someone tampering with the fish if its close to the verge.

The reason I was pumping from the ST to one GB is that its on top of the FT so there is no way I can get a feed to it via SLO from the FT. The other GB thats on the ST I could feed via SLO from the FT and will change to design to achieve that.

So I just will be pumping from the ST direct to the 1 GB above the FT - plan to have yabbies in the ST - do they make much 'solids' mess?

Hi mattyaga

To begin with, and to stop confusion, forget the terms ST and FT.

The system you have proposed, in my eyes, has 2 FT's. However you want to pump the water is really up to you. Use your pump to move water in the most efficient way you can think of to your GB's and return them equally to whichever FT you desire.

What you need to remember in your system lay out is that you need to pump both your FT volumes through the filter/s (GB's) approx every hour or so. However you do this is not important.

Keep the basics in mind. Many people get caught up in how to design a system but the basics are all you need. You have 2 FT's and 3 GB's, if you are using 1 pump you can move water a thousand different ways but the out come will still be similar.

Keep it simple. Pump once... drain however you like.

Buy another small pump... pump the fish tank to the bed above it... drain back to tank...

Pump the other fish tank to the other beds...

Two seperate systems allow for two seperate species... and/or new seasonal stock...

Thanks -thats good to remember the basic requirements. I take it that its not good to mix water from two different species then, and physical seperation (i.e they are in different tanks) is not enough?

Are there certain species that can cohabit (same tank or same water system)? eg yabbies and SP?

Cheers
Matt

I bought a second hand system in the end that came with a 500L GB and a Hydro GB (approx 200L) and a 1000L tank and a 500L tank and 15 mature SP.

Moved it this weekend and moved about 400L of system water in the small tank. So far I've got one large GB running in the system and the 1000L tank.



Did my first test today



pH 7.6
Ammonia 0.25ppm
Nitrites 0
Nitrates 5ppm

The clay media would have been bagged for 12 hours, so hope the bacteria are still active. Plan to add another 500L GB and the 200L GB to the system and incorporate the 500L tank into the return line between the 2 500L GB's (SLO out of it) and use it for smaller fish once this system is established (will be bypassed for now).

Feeding one small handful every 2 days at present and the SP eat it all within a minute. Once the plants get going I'll feed a bit more... Theres some old plants in the GB at the moment just to consume some Nitrate. The water was pretty green with algae when I got it, though has totally cleared up in 2 days since I installed the system (FT is covered in 70% shadecloth and the small hydro GB)

How should the testing kit water be disposed off? can it be put on a garden bed, or down the drain?

Cheers
Matt