Backyard Aquaponics
A place to discuss aquaponics

Why would additives cause the inability to be "organic"? The trick would be to use "organic" additives and then you should be in the clear? I don't believe that KOH is mandatory as I've never used it. I've also never used CaOH in an AP system so don't think that is mandatory either. And I am quite certain there are organic ways to get Fe into the system. Anyway, There are organic sources for potassium, Iron, calcium, and buffering so I don't see how adding "organic" sources of these would cause you to not be Organic.

TC , I agree adding organic supplements do's not make the system non organic.
Peter ,, a closed system ( that is what most Ap systems are) , but can you please explain the magic of the geo-tube ..... it creates ? or makes nutrients more available , in what manner?

Potassium Hydroxide (caustic potash)... very closely related to Sodium Hyroxoide (caustic soda)...

Is an incredibly strong base.... and corrosive... exothermic... and reacts with some metals to produce Hydrogen...

It's the principle ingredient in "natural" soft and liquid soaps.. effectively "lye"...

http://www.lomb.com.au/Potassium%20Hydroxide.pdf

http://www.jtbaker.com/msds/englishhtml/p5884.htm

Why on earth would anyone even think of using it in an aquatic system... for either the effect on fish, plants or hardware (pumps)...

Calcium Hydroxide... commonly known as "slaked lime"... brick layers use it... ...

http://www.jtbaker.com/msds/englishhtml/c0407.htm

Used as a "flocculant" and in waste water treatment... and at times in aquaculture for pond preparation... and sometimes for pH buffering...

Personally I wouldn't go near it in a RAS system either... again it is a very powerful base...

There are just so many other ... safer, easier to use buffering agents available ...

And IMO... neither the fish or the plants derive any benefit from either product... other than pH buffering...

And pond based aquaculture (algael bloom management)... and green water (algae) culture for Tilapia type systems (ala UVI)...

Usually aim for pH of about 8.0.... which might be fine for some limit plant species...

But highly restrictive... and counterproductive in any aquaponics system IMO...

Hydroponic systems operate... for optimum nutrient uptake... around the range of pH 6.2-6.8....

I am so glad this is continuing, sorry I was busy for a few days.

the need for the base, CaOH is that the pH drops due to the oxidation of ammonium, H released into the solution and O2 pulled out..... NH4 --- NO2 produces 4 H+ per molecule.

Yes you can add an organic source of base, but it has to be really fine to get into solution. We use oyster shell in the organic farm, but I cant tell you how long it takes to become available.

Additionally, from my understanding there is not enough Ca in the suspended fish waste (not the solids, because they are removed) to provide for optimal growth, and the same for Fe.

The geotube is a great idea. They are used in dredging operations, pull water soaked soil from a river channel and you need to put it somewhere where the water will drain out.

The geotube has small holes in it, allowing the water to slowly come out, leaving behind the solids.

In a commercial aquaponics system like UVI there is no substrate where the bacteria do their magic. The solids have to be removed or they will attach to the roots of the plants in water and cause areas of anaerobic conditions as the solids decompose using all the O2 to do so.

OK... so rather than just opening up a valve on the fish tank and having the solids run off into some sort of pond you have an automatic value and pump drain the solids into the geotube.

Now, the geotube needs to be on top of a gravel pad, with an impermeable liner under it, but with a drain.

As the solids are decomposed slowly via normal composting and additional water added regularly, the recently liberated nutrients get carried out of the geotube in the water and out, back into the system.

This allows you to capture most of the nutrients in the solid waste and not having to add the Ca and K and Fe.


Of course this is what you are doing with the solid substrate systems most of you have, so the question is why the water culture?

not sure, I hope to see while at the workshop.

I am not sure if there is any experiments showing yields that can compare to the UVI model using an aggregate and the scale of the UVI system.

You eventually end up with some sweet compost as well, that you could sell.

So, what is the Hawaiian group doing, I saw you can buy the system notes for $750 or so...

me, I am a see it kind of guy.

cheers

peter

Yep, shells or shell grit (CaCO3) ... are what most of us use in aquaponics systems to buffer pH Peter.... or potassium BiCarbonate...

It's the Carbonate/BiCarbonate that buffers....

Of course most AP systems are small scale/low volume in relation to aquaculture ponds or UVI style systems....

Calcium deficiencies are very rare... and even rarer in AP systems that use flood & drain... and the mineralisation provided by solids breakdown with the growbed media... is more than adequate for plant needs...

This is one of the principle advantages of this style of system...

Calcium, and many other trace elements & minerals is contained within the uneaten fish feed... or from reaction of the shells/grit buffering....

The use of CaOH in other models... is purely for pH adjustment... on a large scale... not for Ca uptake by the plants AFIK....

Hi Rupertofzo,

I am not sure if there is much Ca in large scale system fish wastes, but yes they use it to alter the ph as well as koh, so they rotate to provide the ca and k not just the oh part

Most of the solids are removed from the system and much of the ca is not available in those systems, so adding is important i think, I have some of the notes from another talk I went to, they do run water tests for all essential elements.

i will be way wiser in a month

cheers

peter

That Geo tube idea sounds interesting. I was thinking about how to make even better use of worms in the AP system and a permiable material tube sounds like it might be perfect. Put some leaves in it and a hand full of worms and place it on top of a grow bed, rout the intake for the bed into it and walla instant worm feeder, solids filter and distrobution all in a neat package. I wonder if it would really work so well.

sounds like a good plan, i have not looked very hard for the material but what I saw looked way to big. But I am sure someone can find it in small lots

pteer

Joel what else do you have growing other than lettuce, can't work it out from the pics, and no progress pic's since ANZAC day so hows it look now? did the rain have any effects on the GB's and plants?

Looks beautiful Nocky.
There are different types of lettuce including oakleaf, cos, red mignonette, green mignonette, baby butterhead, mizuna, parsely (italian), coriander broccoli and chives.
The wind didn't have any impact on the plants, probably because it is clost to ground level, afew leaves blew in.
The trout are doing amazingly well and are soooo fun to feed.

Faye that is a cheap shot at someone in SA I feel
But good to hear, will get up for a look after seeding has finished down this way and things quieten down, but for now any Pic's

+1 for some updated pics please.

Ok, few updated pics on the system. We really need to weigh some of the fish to get an idea, they are getting huge, consumed about 20kg of feed so far. Everything is ticking along nicely, we have harvested a few rafts, but we are leaving some of the plants a little longer than is necessary because we don't have markets to fill.

These pics are almost 2 weeks old already.. Cos are hearting up beautifully, and the second system has really kicked into gear.

Butter crunch have been about the best grower.



The raft lifter works well.



Harvesting lettuce



Not more lettuce.....



All growing well, cos hearting up nicely, especially since this picture.

Nice plant growth. Until you find a market you could always feed the plants back to the fish.

Nicely done guys...