Backyard Aquaponics
A place to discuss aquaponics

It seems that here in SA the opportunities for AP systems are huge. I have completed my small and medium system - this has generated so much interest that I have been asked to convert an old pool on a residential property to an AP system to feed the members of an Ashram (Yoga Centre) as well as a clinical trial centre involved in cancer therapies for disadvantaged South Africans. This task is a bit daunting and the budget is going to be quite tight so if I could have some feedback as to which routes you guys think I should follow I would appreciate it.

The major expense in this project is going to be the growbeds - if there are any weird and wonderful designs out there I would appreciate some feedback - Synapto's pipes are a good idea but to expensive for this setup - I am thinking of building 12m long by 1m wide grow beds that share a common wall all out of brick and mortar - thus the first 'module' when empty would contain 7.2 cubic m of water, we are planning to build four sets of these totaling just off 30 000l of grow bed, which should be enough filter area?

I am concerned over pumping times as well as amount of pumps needed. All of my systems so far run at 15 minute intervals, thus approx 2 minutes on for the pumps to fill grow beds and then 15 minutes off. This is not going to be feasible for the sheer volume of water needing to be shifted, is it advisable to run a pump per a grow bed or possibly a pump per 2 growbed? This gives redundancy in terms of one going down as well as if they ran at staggered intervals a relatively small back up generator could be used in the case of blackouts - thus no downtime.

I will be building two sets of growbeds to start with (14.2 cubic m) so I may have to have a separate solids filter to ensure that bacteria growth and system settling takes as little time as possible. Would you agree? This would run on a much smaller pump but it would run continuously.

Attached a couple of pictures - as much advice as possible would be appreciated.

My idea for bigger systems that I'll be testing in a few weeks (slowly progressing) is that the GB 1 fills over half an hour while GB 2 drains and for the over half hour vice versa. I based this on FnFs flooding regime where he pumped water in to his GBs for three minutes once every hour and then they drained out over the hour.

I believe it will work and it mean you don't need as big a pump because it runs continously rather than in burts.

Stuart

+1 for building growbeds. If you have access to both sides of the bed, 1.5m wide works well.

Its not a case of matching the growbeds to your water volume, its matching them to your fish volume.

Starting off with 14.2m3 of growbeds will be fine. A seperate solids filter will not be required, thats what your huuuge growbeds will do best.

For the pumping, use 2 pumps running to each set of beds, redundancy is the key.

Probably use a water pipe grid over the beds to distribute the water, same as joels system.

14m3 of growbeds = 1400 x 1/2kg fish

[quote="Outbackozzie] Probably use a water pipe grid over the beds to distribute the water, same as joels system.

14m3 of growbeds = 1400 x 1/2kg fish [/quote]

I am planning on putting 2500 Tilapia fingerlings in the system - this will mean that I would have to have the second two grow beds up and running within 2 months to be able to cope with the waste produced as the fish get bigger. 28m3 in total

The water would be distributed via a system similar to Joels including drainage via stand pipe system - ala Joel. Is it really necessary to build a grid of spray bars rather than have one pipe spraying into the growbeds along its length?

Lastly, you mentioned two pumps per grow bed, meaning 8 altogether what would your recommended pump volumes be then for each pump? I was working on have a .75Kw pump attached to each bed - max flow 22 000 litres an hour but I can understand the need for redundancy.

I would also like to run staggered pumping cycles - other wise I'll have huge drops in water levels when all beds are full - do you not forsee a problem with the amount of time it takes to drain (1 hour)? I have found that with slow draining cycles on my existing systems I get fungus on the roots - in addition the water draining as fast as possible should suck air down into the growbeds for oxygenation?

If you have 3 phase power, use that for the pumps, its more efficient aparently.

I was meaning two beds per pump, 10,000lph pump should handle 2 beds ok.

You would probably be able to run the whole system on 3 - 4 of these pumps:

http://www.rockaroundtheblock.com.au/product.asp?pID=451&cID=63
You wont find a better pump for the watts consumed. Even using 4 at once, it only comes to 700 watts and any portable generator can run that.

Because you are using flood and drain you will only need one line down the middle of the beds to distribute the water.

Ive been thinking about using half-shipping containers as growbeds ( thinking being the key word - not enough space .. )

theyre 11m long , just over 2m wide then can be cut down to any height you require .
I wonder how they'd stack up in price ( and labour ) compared to building brick / concrete GBs

they'd need to be coated on the inside with food grade / potable water grade sealer , but then so would anything you build with concrete in it

just an idea

Geeze boris, you make all my ideas look shame !!! I have gone from fibreglassing out my own channels, to Ell Gro, to PVC, to pulling apart pallets and going in for the construction side, but sea containers, way to go dude, can I watch when you have to harvest the middle of the crop

what a great idea ,, you could have small GB for your food and the very large ones could grow flowers or even grass what ever it takes to suport the massive amount of fish you could grow out.....

Crickey boris, I though I liked big AP systems - your crazy

spot on Fishlips - the idea WA for grass initially - I wanted to somehow get my lawn to stay green all the time . easy way to do that - grow it in a growbed hooked up to a monster system !
hehehee

FnF's system takes 1hr to drain mine will be a half hour fill/half hour drain regime. FnF hasn't mentioned any problems with his draining cycle taking the hour.

No matter how slowly the water drains it will still suck air down into the gravel as it empties. Why would a high speed air flow be any better? The air drawn into the gravel bed on the drain cycle will stay there until the fill cycle pushes the air from the GB. Why would air that was drawn down quickly and then hung around for a while be better than air that is slowly drawn in and then pushed out of the GB.

It may be the case, I don't know, but I wouldn't have thought it would make much difference.

+1 stuart, air sucked in over an hour, or air sucked in over 2 mintues, its still the same amount of air. The only thing that differs is the amount of root surface exposed to this air during the hour.

2 minute drained bed gets all the roots exposed within two minutes, the hour drained bed gets only 1/2 the roots exposed after 1/2 an hour.

This probably only becomes a problem in a heavily stocked system, with lots of 'solids' in the water which could block the roots up a bit. You would want maximum 'dry' time in this situation.

fungus might indicate excess food in the tank decomposing in the GB's

+1 for the 3 phase motors, more efficient, cheaper to buy and repair

+1 for the bricks and mortar GB's, C1 might be able to give you some ideas......

Has anyone done any trials to determine optimum times for flood and drain systems, My thinking when developing the timing cycles was that if I had relatively short periods between fills but with quick drains, I would constantly be supplying the plants with refreshed water with a large amount of nutrient and also allowing the roots plenty of time to absorb air. I've always felt that long slow cycles would be detrimental as the water in theory stagnates as well as the roots being submerged for extended periods of time cannot be healthy. I stand to correction over this - so fire away. I am aware of a number of members with long flood / drain cycles with no detrimental effects but is there perhaps a difference in growth rates?

The three phase power and such still needs investigating - the current owners are relatively clueless as to what goes on, on their property. I've basically been handed over a task saying feed these people and if there's too much we'll find some more people to feed. the logistics surrounding the build have been left entirely up to me.

Another recommendation I need, the grow beds will cost more if I build them waist high as in my original plan(working on 1.2m high), do you think that if I made them 40 or 50 cm above ground level to save money that it would be a decision I would regret in the long term?