Backyard Aquaponics
A place to discuss aquaponics

Hi All,

After all the planning and gathering materials I finally got to commission my latest incarnation of my system this afternoon. I'd originally had it in the back corner of my yard using the same tank but pallet racking and 6 inch PVC as a grow bed. http://backyardaquaponics.com/forum/viewtopic.php?t=4451 (not quite NFT not quite flood and drain) It was Pretty unsightly and due to incorrect choice of medium, pump and watering method it had limited success. Don't get me wrong, after further revisions it still worked, just not the greatest. I had my doubts that it would do really well, and even though OBO had given some very sound and accurate advice, I decided to persist with that layout, which in the long run was better because I'd been able to witness EXACTLY WHY and HOW things would go wrong. (big up to OBO for looking out for me, but I had to witness it for myself to fully understand) months later and working at the local hydroponics store a few days a week had taught me massive amounts about horticulture, correct media selection, micro and macro nutrient uptake, and feeding methods.
So with this... I bring you my latest system.

Existing tank, 2400W x 1100D x 750H. Rolled colour bond.
(about 100 yabbies added, still have 5 goldfish and sadly only 10 catfish remain. Very little feeding over the cold months so bugger all growth)

Frame is 70x35 termi-pine, 2600W x 800D x 800H cross braced for rigidity and painted to look pretty, stop rot and prevent leaching of pesticide.

Grow bed is completely removable and approx 2400W x 750D x 300H, (about 500 or so litres) 20mm top-down feeder around the edge of the grow bed, exiting 4mm holes at a spacing of 1 inch apart. Built with recycled F24 19mm form ply, scrubbed, silicon'd, no more gaps'd (from all the form work nail holes) and then painted internally with Gripset 51 potable water sealant. I've painted the grow bed to match the tank. The bed supports itself on the outer edges of the frame held up by only 30mm along the depth, which is plenty because form ply is dead strong and I've knocked it together using 32mm outdoor screws at 150mm spacings. I'm told this will hold near 2 ton of concrete like that from my concreter mates. Media is red scoria pressure washed over and over and over again. (if it wasn't for the high surface area, weight and disolvable mineral content of scoria I'd tell you it's not worth the hours of washing) with a mix of diatomite mixed through the top and mid layer of media for it's disolvable silica content, and as a plus, it just so happens to colour match my GB and tank.

Feeder system is the same Grundfos 460W fluid transfer pump able to pump solids up to 10mm diameter (and catfish fingerling heads so I've covered it with a gutter guard style poly gauze), 32mm outlet stepped to 20mm barbed fitting feeding 20mm silicone food safe heater hose. Method is standard flood and drain with 2 x 90mm guards over 25mm standpipes that step open to a 40mm opening with the base having about a dozen or so 4mm holes drilled around it for final drain. (I chose this method after bulk research over auto syphon as I wanted complete reliability and to conserve electricity) Pump will feed for 15 minutes (outdoor mechanical timer) and stay off for about an hour and 30 minutes. Full flood takes about 8 minutes and full drain takes 22 minutes.
There is a barbed inlet to the manifold for the silicone hose to provide quick access/removal of the pump, tap works allow me to feed the bed, provide recirculation back underneath the GB, and open a purge line that allows to to plug in my 13mm garden hose to water my soil garden if need be.

PHEW! So there we have it, my creation that was born out of learning how NOT to do everything. Lols!
It's in the perfect position for full day sun and plans for next month include a retractable shade blind and a complete conversion to solar power.

I guess the questions to my fellow AP community is... Whattya reckon? and what veggies should I grow in it?!

Cheers,
Kri.

more pics

I told ya it was pic heavy...

mo betterer pix...

and some more pics...

yep... deffo on the pic heavy.

Looks great! What's with the posing bluetongue?

almost finished...

Thanks Kuda,

You caught me mid-upload. That's tickles, my blue tongue (fully liscensed) she's my unit of measure... you know, grow bed is 3 blueys deep by 1 bluey high by 8 blueys wide...
Just a touch of humour.

almost done with the pics.

DONE!
Easy access right at the back door. I don't think i could get it any closer to the kitchen.

So... any ideas for planting this baby out?

Nice job...

So how high is the dolomite limestone going to keep your pH?

Plating right out the kitchen window, and with a likely high pH. Probably best for herbs.
Basil, rosemary, parsley, lettuce, chard, tasoi would probably be a good start and most of those don't seem to complain too much about the higher pH though you might need to add extra iron.

Cheers TClynx,

But it's not Dolamite Limestone... It's Diatomite.
Diatomite is fossilised single cell organisms/algae from millions of years past. It's Austrlian sourced so not quite as good a quality as that found in the USA but it is the freshwater type so compatible with the system. Diatomite (used as a powder for making diatomacious soil and drysorb) has a massive amount of soluable silica in it which plants uptake to multiply and strenghten cell walls. I get what your saying about dolomite raising the ph, but it's a different product. As a new media for us at work we have a few of our customers trialling through the shop to report back results in independant tests. However you have raised a valid question for me, will it effect PH?... I've read the msds and don't recal anything to say so (I know the dust is bad) and PH is critical for hydro growers. But i've also read aquarium hobbyists using diatomite as a filter medium also, and thats one field that is very very picky with PH so to hazard a guess i'd say it won't change too much, but I will be watching it closely and doing an isolated test tomorrow. We've considered silica overdose, but not PH! As a side note though, red scoria was chosen for this system because of it's naturally high iron leaching, (I want to make the AP system stand alone and refrain from adding chelates) we only have one state (VIC) that produces this red volcanic rock to my knowledge (white is produced in QLD but a different substance alltogether) and it's mineral content availability is huge. Thanks for the input hey, you've given me some good food for thought and a little experiment for tomorrow. nice one!

Kri.

Teach me to skim read!!!!! LOL

Learn something every day. I know about Diatomatious earth or fossil shell flower. I'd never seen it called Diatomite and in pebble form before.

Please post your pH results

Yes, I've heard of it used in filters and stuff. Hum, silica I think I should go sprinkle some around my bamboo.

Anyway, looking good.