Backyard Aquaponics
A place to discuss aquaponics

Wow good to see you cant let something go, Mmmm maybe your just argumentitive

Okay firstly, I offered the poster advice regarding what the deficienys could be, if you believe otherwise thats your choice. The fact that you dont believe these could be the problem then thats fine, but just becuase you say it cant be or its ph related doesnt mean it is or isnt

Yes the availabilty of nutrients to plants in water is similiar to that in soil but they are not the same, iron being a classic example, on the standard soil ph chart iron is available all the way up to a ph of 10 "reduced but available", in a hydro chart iron becomes similiarly reduced from 6.8 and unavailable for the plant the moment ph goes over 7.8, manganese in soil is reduced from about 8.5 onwards, the same amount of reduction happens in a hydro system from 6.5 upwards. The rest of the macro and micro nutrients are comparable but they are not the same.

I'm assuming you are referring to the chart produced by M. Edward Muckle

Who asserts that the widely accepted soil based chart is frequently misapplied to water culture applications. His (recent) research (and that done by others), indicate that iron and phosphorous precipitate in nutrient solutions at pH levels above 6.

And that nutrient assimilation rate is further enhanced by the reduction in solution TDS/EC, which reduces osmotic pressure and allows the roots to draw the nutrients "easier".

And further that... the optimum temperature for hydroponic solutions is 24c/75f. At this point, most elements are assimilated highest and atmospheric oxygen is most readily dissolved. Although increases in temperature increase the rate of photosynthesis.

He also asserts that hydroponic systems should for these reasons be kept within the range of 5.1 - 5.9

Such prcatices as recommended by Muckle... are not applicable.. or obtainable within aquaponics... where optimum temperature for many fish species exceeds 24c... and a pH < 6.0 is harmful and ultimately fatal to fish stock..

It is also based upon hydroponic nutrient solutions and the effect of temperature with regard to the "salts" preciptating... and aspects of certain elements... iron, maganese, boron, copper and zinc becoming locked out due to the different "chelation" effect that occurs within soil/mediaand hydroponic systems with regard to pH ...

Also ... Elevated temperatures make some elements more available, but reduce the solution's dissolved oxygen capacity... a critical factor with regard to keeping fish...

Aquaponics does not utilise "nutrients" in the form of hydroponic formulations... and occurs within media based growbeds... as such, my contention is that the "generalised" plant nutrient uptake chart is more applicable than that which pertains to chemically formulated (and pre-chelated) hydroponic mixes...

Oh, and I do have some previous, and current hydroponics experience..







You'll also find that TDS and EC aspects don't translate/relate to aquaponics as they do to hydroponics...

To add further... nutrient availability beyond pH 8.5 ...also becomes similarly inapplicable... as such pH levels would also be detremental/fatal to fish stocks...

As it would to most plant stocks as well...

That all sounds pretty spot on, cannot ascertain on the fish side, because as Ive said before I know very little about fish, nice hydroponics field. We had a few farms over the years approx 400 acres over in Taree, where we grew and sowed crops from the soil and learnt to experiment in hydroponics.

I just get pieved when I see people knock comments made by others in a matter of fact so manner, being the internet it is hard to fully understand a persons personia or demina simply by a post, as they say most of us talk with expressions and hand and body movements more than verbal speech itself. We may have gone of on a tangent without the need for it

All is good

Ditto Simso.. all is good....

Another aspect I didn't think to explain... is that much of the "mineralisation" in our aquaponic systems... takes place by the breakdown of solid wastes... fish wastes and uneaten feed (containing trace elements and minerals)... by compost worms within our media growbeds...

And inclusion of "rock dust" and/or occasional doses of chelated Iron or foliar feeds of seaweed extracts...

A good read - can we maybe stick something in a "The differences between Hydro and AP" thread to keep track of 'em all?

Umm, here are more pics after several days pass... they seem to be getting worst.

That's assuming that those nutrients are present in the system in sufficient quantities so that, when they are available, there is enough to fully satisfy plant requirements. 100% of nothing is still nothing...

Chatty

Pic 1 could be either Sulphur or Potassium. Pic 2 blows that analysis out of the water!! Both those nutrients are relatively mobile in the plant so inconsistent, varied yellowing of the leaves says to me that it isn't either of them.

Is this stuff a legume by any chance?

Chatty

They're Moringa plants... not a legume as as i know...

True enough, but unlike broadcast fertilisers used in soil systems... often depleted by years of mis-management...

Aquaponic systems are constantly refreshed with nutrient and trace element availability... from both feed, faeces... and subsequent mineralisation within the growbeds...

Hence the general abundance of (and constant) growth evident in aquaponic systems...

And it should be remembered that many systems are Calcium supplemented with Calcium carbonate buffers...

Low Calcium, and/or other elements would be just as evident in poor fish growth... as in plant growth... regardless of pH...

So there is sufficient magnesium in fish food for plant growth? If we aren't feeding it to the fish and they're excreting it, it generally isn't making it into the system unless the nutrient is being supplemented - seasol, worm casting, potassium chloride or any other fertiliser!!

I've seen plenty of photos on this forum to suggest that the system isn't as complete as you make out. There are nutrient deficiencies occurring in a number of members systems so to make the sweeping statement that nutrient mineralisation will supply all requirements is clearly not always true. Cold weather can slow the rate of mineralisation in winter and induce a deficiency in an otherwise healthy system.

Certainly the older the system the more robust they seem to become.

Chatty

Often there's sufficient magnesium (and other trace elements) in source water to provide all that is needed for plants growth... and the utilisation of rain water often evidences improved growth for the same reason...

Yes, many members from time to time.... supplement trace elements by the use of Seasol, Rock dust or worm casts... often by the use of worms within the growbeds themselves breaking down uneaten feed, roots and other plant detrius...

Personally, I often top up my systems with clean seawater, a known source rich in trace elements... I also occasionally use EcoRose... a high Potassium source... specifically for a Potassium boost for heavy flowering/fruiting/seeding stages of plant growth....

But more particularly... for the bicarbonate buffering of pH...

But I'd do the same in a hydroponics or soil based system... I just don't need to do so, as regularly... or in the quantities I would do so in such systems... in comparison to aquaponics...

Those member systems that exhibit deficiencies.... are often "young" systems that have as yet not acheived the benefits of mineralisation within the growbeds...

OR more usually are due to nutrient lockout because of pH....

The majority of member systems exhibit abundantly luxurious growth... with no apparent deficiencies... and those which may occur are readily addressed with minimal application of specific products...

My systems require absolutely minimal intervention... as do many other mature systems... but my systems run at pH 6.0 - 6.4...

And I bet all the other mature systems that exhibit continued great growth ... constantly... do so as well ...

look here http://www.hbci.com/~wenonah/min-def/list.htm