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  1. #1
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    Aquaponic system ph level and nutrients

    Hello everyone,

    I want to make an aquaponic growing system at home to grow various kinds of vegetables and am wondering the following:


    • Since different plants have different ph and nutrient needs, how would they grow with one source (the pond would have some mid-point ph level around 6 and nutrient for the plants)?
    • Some plants require higher levels of certain nutrients, is it possible to plan how much the plant is going to "eat"? In terms of nutrient and overall water?
    • Can one plan to have separate ponds in the system to allow different nutrient mixes?


    I hope my questions are clear enough. Anyways, thank you very much in advance for your help and time!

  2. #2
    Aquaponics 101 Oliver's Avatar
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    Plants tend to uptake what they need, as long as those nutrients are present.

    The pH in an Aquaponics System needs to be between 7.0 and 7.5. This is the best balance, as the bacteria need the pH to be above 7.0 in order for them to do their job (read AP-101, tab at top of page).

    The plants have a wide range of acceptable pH. DO (Dissolved Oxygen) is also important and needs to be at least 5 ppm or higher for the bacteria to perform well, and is also needed for the plants. Some plants, like leafy greens, need little DO, but not zero; while others need lots of DO, like tomatoes and peppers. Low levels of DO can cause root rot, a fungus that lives in moist conditions where there is a lack of oxygen.

    Everything else seems to take care of itself. But, it is always good to add some Calcium (lime, if not already in your water supply), Potassium (we use potassium hydroxide) and Chelated Iron; otherwise your leafy greens may be leafy whites along with white cucumbers instead of green ones etc.

    Yes, some plants require higher levels of certain nutrients, like tomatoes and other flowering plants need high levels of Nitrates when flowering. Just make certain that your nitrate level is adequate, 40 ppm for leafy greens, 80 ppm or higher for flowering plants; but once you reach 100 ppm you are starting to push the limit for the fish. Anything over about 150 ppm of Nitrates is toxic for the fish (Tilapia).

    Your use of the term "pond" concerns me a little. We usually call where the fish live a fish tank. Pond implies a large hole in the ground filled with water, which can be used to hold the fish; but it is more difficult to control the chemistry due to the assumed openess and being subjected to the elements, as well as the ground beneath and what else might be growing in there. Aquaponics requires a medium density of fish to water ratio in order to generate enough nutrients to feed the plants. Ponds are generally populated with a low density of fish to water ratio.

    By the way, Aquaponics is a sub-set of BioPonics. BioPonics is the process of converting organic material into plant nutrients and giving them to the plants by way of circulating water. In Aquaponics, fish are part of the conversion process, but with BioPonics fish are optional. Without the fish we have another sub-set of BioPonics called NitraPonics, the conversion of organic nutrients to nitrates using just the bacteria. Chew on that!

    To be continued,

    Oliver
    To measure is to know

  3. #3
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    Thank you very much Oliver! I've started reading the Aquaponics 101 threads, thank you for writing those!

    Indeed, I have used the term "pond" incorrectly. I meant to say fish tank. My intensions are completely internal and for a closed system to eliminate pests as a problem as much as possible.

    Unfortunately, I couldn't find much info on Nitraponics, there is a lot of stuff for Nutraponics, which appears to be a Canadian company. Anyways.

    The main reason I'm asking is because I don't want to grow fish for food. I don't want to kill fish and thus am wondering how to make the best system possible.

    If I want to have a system with decorative fish (I don't want to kill fish) and a variety of plants (potatoes, carrots, onions, tomatoes, cucumbers, peppers, greens, lettuce, peas, and I somehow manage to get EC about 1.8 and ph of about 7-75, good DO (80-100ppm), would you think it would be a balanced system?


    I realize I need to take a very well-paced approach on this, starting off in smaller portions, gradually filling up the tank and the growbeds but in theoretically I could get to such a stage. If I then put a filter system either in the beginning of irrigation of in the end, to monitor and control EC, ph, flow, etc., would that work?


    Of course, I would need to have a very well calculated fish tank, growbed infrastructure (containers, root area, irrigation tubes, sprinklers, mist makers, etc..) and a very well timed water pump.


    I'm planning to build a family year-round plant-based diet greenhouse, powered by solar panels, rainwater harvested water, and aquaponics system. Each plant will be grown in a specific container to best utilize its specific growth characteristics. That would involve using different watering methods but I plan to mostly use aeroponics (both high and low pressure systems, depending on the desired root growth) in vertical growbed "towers". I would also have to think about aeration of the water somehow as well as adding CO2 in the most eco-friendly way (so far I've found various types of fermentation to be the safest bet but I'm still unsure about those)


    A side question on the fish tank: how to deal with fish waste and dead fish? Does the bacteria on the tank bottom take care of that?

    Also, as I want to keep things as clean as possible, I assume by this scheme:
    Click image for larger version. 

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    That I can have the bacteria in a separate tank, not in the growbed containers, correct?



  4. #4
    Aquaponics 101 Oliver's Avatar
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    Regarding Nitraponics, we currently have that url parked. At some point in the future I will be writing more about it. For now, we are running tests on the best way to make the conversion of organic material directly to plant food via a Bio-digester, which will be incorporated into the new system we are currently building after our move here to White Mountains of Arizona. NitraPonics is about taking sources of organic Nitrogen, and through Biological processes, converting it into Nitrates for the plants, all done in water. As stated, NitraPonics is a subset of BioPonics.

    If you search out BioPonics you will find that the term was coined in the 1990s by Tom (late) and Paula Spereano of S & S Farms in Missouri, USA, pioneers of Aquaponics. You will also find that "Bioponics is a new technique of soilless farming pioneered at Bioponica" (2017 quote) on their web site. I thought that I would also claim the "discovery" and "coining" of the phase as well, just recently; but a quick search showed me that several had gone before. It seems that Bioponica didn't do their due diligence before making their claim. So, I will not make that claim. But, I did come upon it independently with the exception of a professor Aecio D'Silva who saw one of our systems in a school and called it AquaBioPonics, which at the time (5 years ago) I didn't like the name but now embrace.

    It just goes to show that the old saying of "there is nothing new under the sun" is still in play. Anyone who has been into Aquaponics for some time and active on Aquapoincs forums has seen all the newbies come along with all kinds of ways to reinvent the wheel (I know, I was one of them), but I can only repeat what Murray Hallam (whom I consider my mentor) told me back 8 years ago, "go with what works and then experiment later".

    The only thing that I am bringing to this old technology is perhaps an engineer's perspective of trying to improve the process. So far it appears that may be the case, at least until I see an article about how someone already did it way back when.

    For the time being, we will only be sharing our NitraPonics progress in our upcoming class this summer, once we have a working model in place.

    As far as EC goes, it is a term used in Hydroponics, where almost every aspect of the nutrient balance is controlled. In Aquaponics we tend to let nature control much of the system chemistry with some husbandry applied, such as keeping the pH within a certain range and adding some minerals as required; as not everything the plants require are in the fish food. Dr. James Rakocy of UVI tried to use only the fish effluent to supply all the plant requirements and found that he needed large quantities fish in order to feed the plants everything they needed and came up with a fish to plant ratio that was growing lots of fish. The main problem with his method was that he was removing most of the fish solid waste, which contain lots of mineral nutrients and provide a source of additional ammonia and therefore Nitrates, equal to or more than what the fish were providing.

    You need to look at your numbers again. DO won't be above 8.5, as that is 100% saturation. Please continue reading Aqauponics 101 tab at the top of this page.

    In short, I think you are over thinking this.

    Oliver
    To measure is to know

  5. #5
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    Thank you very much for your reply, Oliver! I will re-read the Aquaponics 101 several times probably until I actually move to doing something in reality other than planning. So far I'm still trying to understand how it all works! Bioponics sounds exciting, if possible to maintain an organic system for the plants without fish, that would be my preference (I do not eat fish and do not want to breed fish, will do it only for the aquaponics model).

  6. #6
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    id also suggest you can always make more than one aquaponics system ---that way you can grow things in one PH or another PH independently of each other --as long as you keep them close enuff to the middle that the bacteria doesn't go belly up maybe do some of the small 55 gallon drum systems too test ideas on & do smaller scale killing of fish and plants while ya learn --instead of overbuilding a huge system ---not saying you have to start small just a suggestion ---my biggest suggestion though is this ....anything you can see you can build yourself

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