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Balcony kit at Hillview (Qld)

Discussion in 'New Aquaponics systems - off-the-shelf ready to go' started by miadeb, Mar 26, 2010.

  1. miadeb

    miadeb Member

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    While your feet are up and a beer is in hand there are practical things you might still ponder. What if there be a better way?

    There are those on the forum reporting ph going up, some down and others staying the same. Why? Most of us pass water through an inert media and leaving out those in other climates, looking for those also likely outdoors with winter cold, there are some reporting their ph does not drift. The only factor left is choice of plants. I chose to work with a restricted range and like what grows best without additives as these will be pulling the most out of the water. Brahmi does well and now covers a half of one of the three grow beds. I am working with the idea that this plant operates with ammonium only and generates acidity. The rest of the beds operate with more of a poly culture and their section likely stays neutral.

    It is possible that if I did nothing the ph might drift to a lower stable state from the current 6.5 maintained by lime injections, as the increasing acidity might have a moderating effect and see ph plateau somewhere.

    It is possible that if I weeded out the brahmi the system might be more ph stable.

    It is possible that if I added nitrate to boost the nitrate side of the equation (my limited searching found nitrate uptake ought to induce alkalinity) then I could do away with the lime by adding say potassium nitrate instead.

    There may be still more options but I have one that is proven and until I have evidence of something better I will stick with lime. Many of our native fish live in hard water so liming may have no long term effect.
     
  2. miadeb

    miadeb Member

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    July has begun with frost over the grow beds. Sections of the Brahmi turned black by the afternoon of the first day of frost (-3C). Fish tank temperature went down to 14C and fish have stopped feeding. I do not expect to feed them again till August if this winter follows the usual pattern. I will be checking water temperature more often now looking for any feeding opportunities.

    Have almost finished harvesting beetroot. It is now added to my list of acceptable grow bed plants as its roots are not extensive and come up mostly clear of clay balls. Where at warmer times the roots would come up with some worms there are now none.

    The beetroot tubers filled out faster in the grow bed than in the hydro unit where seedlings from the same punnet were planted at the same time. The grow bed leaves started with greater turgor and this was a disadvantage on windy days when gusts rolled the plants onto their sides and swiveled them about their tap root. The leaves in the grow bed beetroot were coarser and looked less appetizing than those in the hydro unit. Those leaves went to the goats.

    Sticking with plants that come up more cleanly appears to be paying off as there is less ponding this year than previously. There is a build up of a permanently flooded zone evident when a hole is made and the water level is watched as the bed drains. It is not draining with any variation in water level back towards the inlet over about a third of the bed. So far I am not seeing any difference in performance of plants in this area from the same at the siphon end. I conclude there is some flow out of the permanently flooded zone only not fast enough to create a fluctuation in water level.
     
  3. miadeb

    miadeb Member

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    Minimum daily temperatures have risen over the past week to 16C with tank temperature rising to 18C. Silvers started eating and I fed them way more pellets than I normally would for 3 days before the minimum temperature plummeted to 1C taking down the tank temperature and putting the silvers off their feed again.

    There was a price to pay for the heavier feeding. More waste and an off smell to the water. My primary water test is sight. I like the water to be crystal clear. Normally I feed less if on opening the lid, flooding the tank with light to startle the fish, there is waste lifted off the bottom. It takes time for it to be moved across the bottom by fish movement and any swirl induced by flow from the grow beds, to be moved to the pump and up to the grow beds. If the quantity kicked up by the fish is seen to be increasing then the feed rate is exceeding the clearing rate and such accumulation is a level of risk that I like to avoid. There are two ways this can be achieved; less feed, or eat some fish.

    I net the fish with the largest mesh I could find to allow the smaller to escape. To avoid stress I take whatever is caught in the net and with the current mesh the fish can be as small as 150 to 200 grams. Trying to get them out of the net and back into the water is difficult if their fins and gills are caught. This has seen some fish die so we put them to plate no matter how small. I find small fish are less bother beheaded with a knife of the style using carborundum particles along the cutting edge in a sawing movement. They are too small and slippery to safely prepare with a sharp knife. I do not try to scale them. They go into a spirit burner heated smoker box and when done are skinned and the respective fins pulled away to leave meat on the backbone best picked off with fingers.

    Crystal clear water allows fish behavior to be observed, a prerequisite to knowing if they are likely to feed. When not interested they keep to the darker corners. If hungry they will venture out. If that is happening I throw a pinch of pellets in. If a good number show interest I will put more in watching the bottom to see if there is any uneaten buildup. Go too far and cloudy water may follow.

    The forum posits various temperatures at which things happen and feeding behavior is said to change variously at 17C and 15C. Do a search with the search engine SCIRUS looking for silver perch growth rates and you will find research measuring feed uptake at temperatures down below 10C. The real world is a spectrum of grey and the numbers on the forum only a guide. Watch your fish for signs of interest and do not worry when they do not feed. Silver perch are out of the Murray Darling system and with its variation in at least the upper reaches of the Darling, the silvers have evolved as a resilient fish.
     
  4. Murray

    Murray Site Admin Staff Member

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    Thanks for that post MiaDeb.
    My tank temps vary depending on which fish I have. I have been keeping my Jades above 16 this winter. Currently the Jade tanks are at around 18 and they are not feeding all that well, but enough.
    One system has 250 Silvers in a 2500 ltr tank. They were new little fish from the hatchery in March so they are still small. Their water temp today is 13 and they are still taking feed every day but at lower rates.

    Silvers are just great, more sensitive to low DO levels than Jades, but more cold tolerant. Slower growing than Jades. Delightful on the plate.

    PS, my Murray Cod (100) are in a 1250 ltr tank, temp is 16 today. Small 300 watt heater is keeping it just above 15 so that are feeding every day and growing well. I did have them split up into two tanks but have put them back together today while I change some systems around in preparation for our upcoming training course. In a few days I will split them into 80 and 20. The 20 were in an unheated tank where the temp has been down to 10. They were not eating at 10c.
     
  5. RupertofOZ

    RupertofOZ New Member

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    Deb, you've made reference to this several times...

    Can you post the links to this suggestion???

    It runs contrary to everything I've ever seen published relating to the underlying chemistry of the nitrification process....

    And contrary to every chemical property and affinity of the nitrate compound as I understand it....
     
  6. miadeb

    miadeb Member

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    I'd like to try another species Murray but we not only face the temperature problem, there is a power problem where our temperatures are milder. We live on the front of a ridge into the valley so cold air flows away downhill and we have a range of subtropical fruit trees on the ridge. A passively heated poly tunnel might keep temperatures up enough. But a system up here has to run on solar.

    Not offhand.

    Rupert I am not referring to nitrification but to uptake at plant roots. The same situation as exists in hydroponics. Does the ph of water in a system supporting mature plants go up, down or stay the same in hydroponics? If it goes up then the internet story may be valid and nitrate addition might be effective in aquaponics. Down and I am stuck with lime. So the matter is resolved with a one word answer; up, down, or unaffected.
     
  7. RupertofOZ

    RupertofOZ New Member

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    OK... where to start....

    Uptake by roots.... generally in early seed development... ammonium is the preferential uptake in plant systems... and some uptake does continue throughout plant growth... (for reasons I'll outline later)...

    But generally once leaf structure has developed the principle uptake is nitrates (NO3)... transported from the roots to the leaves and in combination with phosphorus... and sunlight/photosynthesis... ATP conversion into sugars/starchs...

    And therein lies the first hint as what variations might occur.... sunlight/photsynthetic processes.... driven by sunlight.....

    Things change during the night.. when photsynthesis is obviously not ocurring.... in terms of temperature, pH, oxygen.... (and carbon dioxide)...all essentially diurnal processes....

    So, to put it into a "hydroponic" context... which might relate to any article you saw.... (what follows is cribbed from my various notes)


    Yes..... pH can rise in hydroponic nutrient solutions.... especially as they become spent... or effected by temperature/oxygen... ( direct relationship)....


    In a nutshell...

    The ratio in uptake of anions (negatively charged nutrients) and cations (positively charged nutrients) by plants may cause substantial shifts in pH.

    In general, an excess of cation over anion leads to a decrease in pH, whereas an excess of anion over cation uptake leads to an increase in pH.

    As nitrogen may be supplied either as a cation (ammonium - NH4+) or an anion (nitrate - NO3-), the ratio of these two forms of nitrogen in the nutrient solution can have large effects on both the rate and direction of pH changes with time....

    And in hydroponics...this shift in pH can be surprisingly fast.


    Daylight photosynthesis produces hydrogen ions which can cause the nutrient acidity to increase (lowering the pH).

    At dusk photosynthesis stops and the plants increase their rate of respiration and this coupled with the respiration of micro organisms and the decomposition of organic matter uses up the hydrogen ions so the acidity of the solution tends to decrease (pH rises).

    In low light (overcast days or indoor growing environments) plants take up more potassium and phosphorous from the nutrient solution so the acidity increases (pH drops).

    In strong intense light (clear sunny days) plants take up more nitrogen from the nutrient solution so the acidity decreases (pH rises).


    Nitrogen is the essential inorganic nutrient required in the largest quantity by plants. Most plants are able to absorb either nitrate (NO3-) or ammonium (NH4+) or both.

    NH4+ as the sole source of nitrogen or in excess is deleterious to the growth of many plant species.

    Some plants yield better when supplied with a mixture of NH4+ (ammonium) and NO3- (nitrate) compared to NO3- alone....

    And a combination of NH4+ and NO3- can be used to buffer against changes in pH.

    (hold this thought...as it has great relevance to AP)


    Hydroponic nutrient products are often 2 part mixes... for this very reason....

    The first for early seedling development... essentially urea, which produces ammonia/ammonium....

    The second part being primarily trace elements and nitrates... but with a degree of ammonium provision (usually urea based)

    Plants grown in nutrient solution containing only NO3- as the sole nitrogen source tend to increase solution pH - hence (in a hydro nutrient context)...the need to add acid.

    And hence... in a hydroponic context... it could be said that Nitrates... increase pH....


    But.... remember... in an aquaponics context... the fish are continually producing ammonia... regardless of day/night... and/or any other diurnal processess....

    Similarly... the nitrification occuring as part of our bio-filtration (grow beds/filters).... continues... producing Nitrates....

    And generally, in an aquaponics context... nitrates are removed by our plant growth... and acidification is usually the trend...

    Elevated levels of nitrates in an aquaponics system... say for example... once summer crops are removed... could raise pH during winter...

    But generally the ongoing nitrate production is lowered, and offset... by the lower nitrification due to lower metabolic and feed rates...

    And you'll usually see most mature systems have test readings of 0,0,0... and usually at a low pH...


    Systems that consistantly show nitrate readings, or periodically elevated readings... are essentially imbalanced... or perhaps more correctly... on the edge of imbalance....

    They may be sufficient in terms of nitrifiction capacity.. but barely so... and probably near the edge of bacterial collapse...

    Whether that be due to low carbonate buffering (carobn debt).. oxygen debt... or both...

    And that's the primary problem with over stocking... over time...


    There are other inter-reactions between Calcium, Potassium and Phosphorus... and pH...that influence plant growth... and one of the reasons I don't support the use of Phosphoric acid as a pH buffer...

    But they're another issue... suffice to say though... the issues underlie the recommendations to alternate between a Calcium and Potassium buffer for pH... generally using Calcium and Potassium Hydroxide... or carbonate compounds of both...
     
    Last edited: Jul 21, 2012
  8. RupertofOZ

    RupertofOZ New Member

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    So to sum up Miadeb.... while it could be said that adding "nitrates" might raise your pH.... you would be altering the balance of your system... and probably continually "chasing your tail"...

    While not adressing the underlying cause....

    You are far better off just addressing your pH problem with the addition of Calcium and Potassium buffers....

    If your continuing pH imbalance is a problem.. as far as you're concerned....

    Lower your fish density....
     
  9. miadeb

    miadeb Member

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    With a short answer to the question would have been good. I scanned the post a number of times and took comfort from the following.

    I am now convinced that the quickest way to deal with this is to try it. I have Bok Choi in one grow bed that is yellowed, stunted, and bolting to seed, nothing like the more normal showing of Bok Choi out in the dirt. Those symptoms are listed in my references as indicative of nitrogen deficiency, so some added nitrate may do no harm so long as it is not ammonium nitrate.

    This looks like a good point at which to present some thoughts regarding any need to know science to do AP. Clearly Rupert likes his science. I to, and I have followed various of its threads over fifty years. And over the past twenty years we have propagated plants and bred animals, currently breeding cattle, goats, geese, ducks and chooks, along with tending to some 100 fruit and nut trees, so that I say with confidence the the short answer to the question, do I need to know any science, is no.

    Farming is informed by tradition and science but at the day to day level it only involves observation, sometimes measurement and reference to a calender, to indicate what actions you need to undertake. The list of things to do is usually short and might be made shorter by what goals you set. Some of what others do might be ignored. Once you have learned what to look for and know what to do if the looking indicated its need, no more needs be learnt. From then on it is repetition. In AP the things to be seen and the measurements that can be made are few. The list of actions that can be performed are likewise few. Of all the things we do here to have a harvest, doing AP is the easiest. It, like the other of our activities, can be done without science. That can be left to others. They will tell you when they have found something new to look for or to measure. You can skip the science threads on the forum.
     
  10. RupertofOZ

    RupertofOZ New Member

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    Miadeb... your original question.. and premise... related to a suggestion that nitrates would raise pH... and thus counter your continually falling pH in your aquaponics system....

    While it is true to some extent that pH can rise... in a bucket of (near spent) hydroponic chemicals.... many of which are nitrate based....

    It is countered in hydroponics by refreshing the nutrient solution.. because it's not an optimal situation....

    My post was "lengthy"... in order to compare the processess in hydroponics and aquaponics.... and to highlight that there are differences...

    You seem to have either misunderstood the post... or just grabbed hold of the one sentance that supports your belief...

    If anything... ammonium nitrate.. or even calcium, or potassium nitrate...would be the preferred additive(s)... but ammonium nitrate could be potentially dangerous in an AP system, especially one that is highly stocked....

    Regardless.... of any "nitrate" additions.... your nitrification will continue to lower your pH...

    And there will still be a need to buffer accordingly.... and those buffers are necessary for bacterial growth/survival....

    Nitrates will not... maintain your bacterial colony... or prevent pH from falling... and excess nitrates can be detremental to plant growth...

    With the pH you are reporting... you should not be seeing any trace element deficiencies in your plants...

    Do you add any chelated iron... and/or Seasol... to your system at all...
     
  11. miadeb

    miadeb Member

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    When the subject is AP I do not have any beliefs. I am a skeptic. All this started when I wondered what the forum was telling me might mean.

    Many report their pH dropping and replies to them include the statement that nitrification bacteria reduce pH. You have confirmed this.

    There are three entities talked about in AP water, fish, bacteria and plants. Some people have claimed that their pH is stable. No one has suggested that the fish have any significant impact on pH. If there be balance there is only the plants to create it. If the bacteria take pH one way then these people are either wrong in their observation or the plants do go the other way. This does not surprise me as nature has a way of doing things by pathways that restore balance. If the bacteria are producing acidic water then are the plants alkalizing it?

    When I apply what I know of ammonia in water, its conversion to ammonium, if I was asked to predict water pH after plant extraction of ammonium, I would predict an alkaline solution. Clearly this is at odds with what the forum tells me and what I observe in my system. I reject my understanding of the science and in being made aware of my limitations I tend not to believe anything I come up with as an explanation of what is going on in AP. On that basis I also reject anyone else's explanation. I take my science only from those with relevant qualifications and good standing amongst their peers.

    So does anyone truly have balance in the sense that they do not buffer? If they do have it then it suggests to me that nitrate uptake leaves an alkaline solution. At this point I referred to the internet for some further information. The science was clearly going to take some time to isolate in a form I could understand as conclusive, and the doing of it to see if there be a favorable outcome so easy taht I decided to go with the test. When in doubt, test it out.

    The idea that nitrate uptake induces alkalinity fits another observation. I need more lime in winter. In winter the bacteria are less active and nitrate production can be expected to fall off. I speculated that Brahmi was an ammonium uptake plant and if its uptake process is the same as that employed by the bacteria, nature often makes use of the same mechanisms, it will induce acidity without a parallel nitrate path to balance it. The system will go acidic faster and need more buffering in the cold. Someone suggested seedling plants start with ammonium uptake before switching to nitrate. Then those like me who direct sow seed to take seedlings through their ammonium phase in the grow bed have created another way in which an imbalance might follow.

    Rupert, might I suggest you should remember where you are when choosing to make a post. This is the 'off-the-shelf' section of the forum. This is where potential clients seek to know the experience of others before committing to a purchase. Your focus on science is wasted in a population that does not study science. It likely only confuses them. How many prospects have you turned away? It is so unnecessary. In the main what people want to know is what AP husbandry will involve them in. It is not science. What new comers seek is knowledge of what steps keep a system on track and how hard those steps are to implement. We have four produce stores in town. We have never been expected to listen to a scientific spiel when seeking advice about a problem with animals and the same is true with plants at a nursery. Their business model ought to be your own. Do science on the forum, but keep it off on a thread of your own.
     
  12. RupertofOZ

    RupertofOZ New Member

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    Miadeb, I appreciate your comments regarding this being your thread.. although I don't really understand your reference to "off-the-shelf... but regardless...

    I posted with some science.... because you were alluding to a suggested scientific post on the internet... which seemed to negate all the accepted underlying known principles of nitrification...

    And because I believe you are in error,or have misinterpreted what you have read...

    I'd be happy to take the discussion into a thread of it's own....

    Please could you post the link to internet site that suggests that "nitrate uptake leaves an alkaline solution"...

    And could you also post what you apply, and know of "water in ammonia, it's conversion to ammonium"....

    Both, or either may help reveal why, or where your beliefs differ from accepted viewpoints...

    In the interim... I was merely posting in response to your posts.... and attempting to help... both yourself, and any others that might read this thread...

    And for those that might buy "off-the-shelf:... and/or have no interest in "science".... then surely it is of paramount importance... that they are not possibly mis-lead... by suggestions of science that might not be correct...
     
  13. RupertofOZ

    RupertofOZ New Member

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    I'm sorry though... I just can't let this statement pass....

    The fish ARE the most significant impact on pH....

    They are the primary, almost exclusive source... of ammonia... and eventual nitrification and acidifcation...

    The nitrification (and acidification)... process is not exclusive to aquaponics.... it applies equally to aquaria... and aquaculture.... and has been widely researched and published... for decades...

    One of the fundamentals of Aquaculture... particularly RAS.... is pH buffer addition to counter the nitrification/acidification....
     
    Last edited: Jul 31, 2012
  14. Walks-In-Storms

    Walks-In-Storms New Member

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    Most interested in the subject as I am, I'd also like to see that information....
    Thanks for the suggestion (and the separate "thread" as well).
     
  15. Walks-In-Storms

    Walks-In-Storms New Member

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    And "ditto" my last here...
     
  16. miadeb

    miadeb Member

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    I will respond to the last two posts shortly. This post is to put up something more interesting.

    I posted earlier on this thread that we had planted both beetroot and leeks from the same punnets, half each into an AP grow bed and a hydroponic (HP) unit. We are now harvesting the HP beetroot, some weeks behind the AP beetroot. The AP leeks are clearly doing better than those in HP, but this may be unremarkable because the leeks there are too shaded.

    I posted earlier that we had a permanently flooded zone back towards the grow bed inlet. Beetroot in this region grew to harvest the fastest, whilst beetroot around the siphon, in the full flood and drain zone, lag behind those in HP. The leeks are showing the reverse preference, so in future we will plant beets into a permanently flooded area and the leeks into the full flood and drain zone for best alround performance.

    Lettuce, Bok Choi and onions are not showing any difference despite staddling the two zones.

    I am glad we did not rush ahead with filters. Some plants are clearly not fussed if they be in one zone or the other and the extra effort with filters may not have been worth it. The filters might allow more feed through the system, and could be good for increased overall production, but we are not in a position to test this. Another system side-by-side would be good for comparisons.

    I am glad we stuck with Murray's design, keeping the point entry for fish tank water into the grow bed, decried above by a naysayer, otherwise we would not have the laterally segmented arrangement now in place, and the different preferences of leeks and beetroot might not have become evident.

    I could speculate as to why the above observations might be so, but that only generates angst for some. I will say that at the time the above was seen I was reading a book by Albert Howard titled Soil and Health, published around 1947, and was reminded of the other mechanisms for nitrogen uptake that are not mentioned on the forum. Howard is said to have conceived the principles of organic agriculture. Do an internet search looking for plant root symbiotics if you want to speculate why AP beetroot in fish waste does better than HP. And no I will not put up any URLs. They change over time to be useless. This is a mine field, one for an informed searcher, a searcher prepared to drill down into increasingly complex biochemistry. I am not competent to extract a definitive set of URLs, or to make a set of notes to wave at the forum. I am satisfied there is a result that I can take advantage of.

    Murray has suggested a number of times that fish waste is something of a resource. I think the beetroot performance in Ap against Hp illustrates his point; that the fish waste might be as much a help as a hindrance.
     
  17. RupertofOZ

    RupertofOZ New Member

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    Don't quite understand what you're saying here miadeb...
     
  18. RupertofOZ

    RupertofOZ New Member

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    I wasn't "decrying", or "naysaying" "Murrays" design... or the single entry point at all...

    (it's not really "Murray's design"... just his implementation/preference... other people do it as well)

    I just pointed out that from my, and others, experience.... that it could result in exactly the situation you were reporting...

    If by chance... it's led to some beneficial result for you.... then great...

    There's more than one way to skin a cat....

    Personally, I've not found a problem growing either plants... using a different method of water distribution... but I've not tried to create, or inadvertantly ended up in a situation whereby I've seen the results you report...

    No matter... if it works for you... great...
     
  19. Castaway

    Castaway Senior Member

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    I think Miadeb might be alluding perhaps to mycorrhiza funghi which in healthy organic soils have a connection with the health of the plants.

    There's a lot more that goes on under the soil than can be offered from a bag of NPK bought at Bunnings...:)
     
  20. RupertofOZ

    RupertofOZ New Member

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    Ain't that the truth.... that's the wonderful nature... of nature... :D
     

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