Tomer from Karkur

[GaryD]

Tomer,


.....the next generation is almost ready, being built inside a wooden crate, and with a neater collection box. seems like such a simple thing, a biopod, yet i find myself spending hours on end changing and turning and fixing and adjusting..
That's the downside of being an innovator. I've no sooner thought of an idea than I'm tweaking it....often before I've had a chance to get it built.


still having plant deficiencies.. that is surly my weakest link. just don't manage to find the perfect additive.. any secret grandma recipes??
What's your pH?

Are you returning your mineralized solids to your system?


btw - about your signature -
Bill Bryson quoted in his excellent "a short history of nearly everything" something similar regarding the acceptance of a new scientific discovery (and I paraphrase shamelessly) - first critics says that it cannot be true, then they acknowledge it is true but say it isn't important, and when the importance is obvious, they go on and give the credit to someone else..
I'm always amused by that tendency. The most important thing is that the important ideas put clean fresh food on the table.

Gary

[Tomer]

Hi Gary
PH is fairly constant around the 7.5 mark. seems like a nutrient deficiency to me, probably mostly P as Tuff is a substrate that tends to absorb it, thus both hindering the nitrification process and the plant health.. i'm playing on that first
solids is maybe an issue as well, as they get stopped at the matala filter, so mostly dissolved inorganics get through.. how do you utilize the solids? water em down and pour over the substrate?
a question of a different nature - when i calculate a fish tank size for a raft or GB system, I normally go back to front - first I see how many sq meters of growing area i want, then I see how much feed (I go by 60 grms per sq meter) i will give, extrapolate how many fish i can grow and thus which ish tank volume i will need.
so the question - what is the calculation for NFT? assuming i want a 500 hole system, how do i calculate fish biomass? are they parameters to go by?
thanxx

[GaryD]

Hi Tomer,


PH is fairly constant around the 7.5 mark. seems like a nutrient deficiency to me, probably mostly P as Tuff is a substrate that tends to absorb it, thus both hindering the nitrification process and the plant health.. i'm playing on that first
At 7.5, some micro-nutrients will be unavailable to your plants. Iron is definitely locked up. You can read a blog post that I wrote on The Effect of pH on Nutrient Availability (http://www.microponics.net.au/?p=364).


solids is maybe an issue as well, as they get stopped at the matala filter, so mostly dissolved inorganics get through.. how do you utilize the solids? water em down and pour over the substrate?
Once you've removed the nutrients from the solids (through aerobic digestion), the remaining sludge serves no worthwhile purpose and should be dumped in your compost heap or worm bed.


a question of a different nature - when i calculate a fish tank size for a raft or GB system, I normally go back to front - first I see how many sq meters of growing area i want, then I see how much feed (I go by 60 grms per sq meter) i will give, extrapolate how many fish i can grow and thus which ish tank volume i will need.
so the question - what is the calculation for NFT? assuming i want a 500 hole system, how do i calculate fish biomass? are they parameters to go by?
Tomer, we've been looking at a Backyard Systems Design Tool (http://www.aquaponicshq.com/forums/showthread.php/4275-Backyard-System-Design-Tool) developed by an Australian scientist Dr Wilson Lennard which should be helpful in developing a useful starting point.

My experience of NFT is limited to our 48 hole backyard unit......where we found that we could grow lettuce and soft herbs with very modest nutrient levels.

Gary

[Tomer]

Hi Gary
fantastic. my respects to the Doc. thanks 4 the post
PH has been higher than i suspected lately, closer to 8. can't figure out why, perhaps i don't feed enough.. definitely an issue. I added some phosphoric acid today, hope it helps.
from the calculation i made i will need 60 kg's of fish to support the 500 holes assuming i feed 60 grms of feed per sq meter (if i can use that sizing with nft..) at 2% body weight a day (32% protien).. what is tank volume you would recommend for supporting the 60 kg's?
assuming there will be mineralization and filtration of course
ok.. going to dive into the doctors prescription
T

[GaryD]

Hi Tomer,

I'm sure Wilson will appreciate your thanks.

If your pH keeps rising that suggests one of two things.......your source water contains high levels of minerals (hard) or your media is leaching and elevating your pH.


from the calculation i made i will need 60 kg's of fish to support the 500 holes assuming i feed 60 grms of feed per sq meter (if i can use that sizing with nft..) at 2% body weight a day (32% protien).. what is tank volume you would recommend for supporting the 60 kg's?
The size of the tank is not the only consideration (or even the real issue)......it's the capacity of your bio-filtration to cope with the waste that is generated by the feed (coupled with your ability to keep dissolved oxygen at sustainable levels).

Play with the Design Tool a bit and see what that does for you. Post some numbers and we'll work from there.

Gary

[Tomer]

Hi Gary
well, i have meddled with the design tool, but must say it's a bit confusing
I understand the ratios regarding the media grow beds, but not so much when i want to grow in floating raft's or NFT
another question - when the program suggests the fish tank volume, is that based on the fish density i specified? ie - if i want to grow 20 kg / cbm, and the program suggest a tank size of 3 cbm, does that mean that i should grow the 20 kg's in 3 cbm or that for the amount of plants i will need 60 kg fish?
hope i'm clear, i manage even to confuse myself
what i really want to know is this:
I have an area of 25 sq meters (6x4.5), in which i would like to grow as many lettuce heads as possible in an NFT system. if i need 20-25 cm between each lettuce, i assume i can grow 20-25 lettuces per square meter. so let's say i'm aiming at a 400-500 lettuce farm. from here i want to know the amount of fish i will require for ample plant nutrition, for as you say to balance the biomass.
what i did not understand is the ratios when it comes to using NFT's.
a fingerling for your thoughts..

[Tomer]

Oh - and regarding the PH
it's still stupid high, reaching 8
I have been dosing with phosphoric acid but i just can't keep it down
i guess the tuff is absorbing the phosphorous while releasing Mg (if I am not mistaken)
strange how it was fine and suddenly it just sort of 'collapsed'
but i guess that's how it is in ecosystems
and the plants really look like they don't like it
be happy for some thoughts

[GaryD]

Hi Tomer,

Have you done hardness tests on your source water? If your water is mineralised, you'll need to buffer it before you can hope to stabilise your pH.

Gary

[Tomer]

Hi Gary
yes, i have checked the source water, and the PH is high. I hoped the acidity of the fish waste and nitrification would compensate for it, but it doesn't.
so i guess your right, I will have to buffer the incoming water source..
question - if i spray sesol or something equivalent on the leaves, will that give the plants a break?

[GaryD]

Hi Tomer,

While you're sorting out your pH problems, you can supplement with Seasol or Maxicrop.

Gary

[Tomer]

Hi
well, this is getting frustrating. lot's of the greens turned yellow (literally), and mostly in one growbed (?!).
been adding the doses of the P-acid, but the PH just doesn't seem to want to go down.
I supplement with the local variety of sesol, but not to great success...
back to the basics. ordered some K, Ca and more P test kits, to find out what is missing, beside the high PH.
another issue - in the biopod been getting similar looking grubs but not exactly the BSF model.. they're smaller and somewhat spikier. any ideas? different fly? different larval stage? just curious.. there still great fish chow
good Sunday
Tomer

14801481

[Tomer]

Hi
some recent pics of recent projects. the shabby looking ones are in a youth village for comparing aquaponic methods (F&D, Floating raft & NFT) to conventional methods. look at those cucumbers grow!
the one before last is in a residence, before the planting. the last one is mini decorative systems we are trying, though not sure i'm into that...
cheers




148214831484148514861487