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Nitrates High

Discussion in 'Commercial Systems' started by Stacy Hayes, Sep 27, 2015.

  1. Stacy Hayes

    Stacy Hayes New Member

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    My name is Stacy Hayes. I am hoping to get some help. I have a 10,000 gallon system with a fish tank that is about 6000 gallons and 24 gravel grow beds that total 192 ft long 4 ft wide and 12 inches deep. 18 of them are fill and drain beds with 6 that are deep water. I also have 9 deep water raft beds totaling 72 feet in length. I started out with 1850 blue tilapia fry and have lost a few due to underfeeding trying to keep nitrates down. I have finally got all the beds planted and was hoping that would put everything in running order. My api test kit shows ph 7.0-7.2 ammonia 0 nitrites 0 Nitrates is bright red. so I can't really know what the number is. Can someone tell me what to do to get nitrates down or should I wait till grow beds get up growing good?
     
    Last edited: Sep 27, 2015
  2. Stacy Hayes

    Stacy Hayes New Member

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    I bought Murray's videos and basically went by them except ended up going with loop syphons instead of bell syphons and built system out of wood and liners instead of totes because it was so much larger that what was built on videos.
     
  3. Murray

    Murray Site Admin Staff Member

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    The nitrates will drop when the plants take off. You will have too many fish for that system so you need to be aware and harvest any that reach any sort of size. If you have plenty of water perhaps you could dump some water and add some fresh.
    But.....make sure you do the NITRATE test exactly according to instructions, otherwise bad readings will result.
     
  4. Stacy Hayes

    Stacy Hayes New Member

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    The system is 10,ooo gallons. How many fish should I need at maturity?
     
  5. Terra

    Terra Active Member

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    Ask 10 people you will likely get 10 answers

    Stock your system on filtration ability rather than water volume usually a "Wet Gravel" formula

    Your water tests will guide you of course but as your fish grow and you feed more the whole equation changes

    As i dont know your system or how much experience you have , I would say start with a fish per 20 Litres of wet gravel and proceed from there If you prefilter with a swirl or radial filter or a settling tank ect ect you can run more

    Its like the how long is a piece of string

    Lots of variables that can influence stocking

    eg some say under 18 degrees C water Temp the nitrifying bacteria lose 50% of their ability and drop off more as Temperature drops to no activity at 4C .

    So if your system runs at 24C all year it will have way more capacity than mine which runs cold to very cold for half the year .
     
  6. Stacy Hayes

    Stacy Hayes New Member

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    We will have more cool to cold than hot weather. Less sun in winter.
     
  7. Stacy Hayes

    Stacy Hayes New Member

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    What should my nitrates run?? I have have never built or ran any size system before.
     
  8. Terra

    Terra Active Member

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    My understanding is Tilapia are very tough fish , so probably just fill your growbeds up with hungry plants and wait .

    If you have plenty of water you could do a part water change to bring the nitrates back to a colour you can score , if its off the chart it could be OFF THE CHART.

    This can happen the other end with Ph it goes off the colour chart and it can be a long way off .

    So as with everything in life "Do less sooner" and keep on top of your readings to minimise potential problems later on .

    I generally run my systems in the mid orange colour range (nitrates)

    In the ideal world all your tests would be zero and your system is in perfect balance

    Then of course we have no reserves , so for example we are about to plant our tomatoes which are hungry feeders so my system would be behind and be trying to catch up if it was running at zero .

    Take some photos and post them , use the upload a file button , may need to resize them .
     
  9. Ringer

    Ringer Active Member

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    Hi Stacy,
    In response to your stocking rate question , Yabbies4me has done some great work on formulas for calculating fish numbers in relation to wet grow media volume. Just send him a P.M. I'm sure he will help.
    In regards to your excess nitrate, sounds like the huge volume of gravel approx 15000l of wet gravel you have in comparison to the volume of water approx 48000l and fish numbers lets say 1800 ish, is a little fish heavy (for the media not the water)
    Approx breakdown of your numbers:
    1 x fish per 26.5L of water (just under recommended max.)
    1 x fish per 8.5L of wet gravel (over double the recommended number)
    Looking at these ratios your fish to water looks ok , and at a glance your gravel to fish seems a little fish heavy. Now having said that , the test results shown suggest your microbial culture is able to handle the ammonia the fish are excreting right now . More ammonia will be produced as the fish grow and this slight imbalance my grow. I'd recommend some heavyish planting to start trying to use up more of that available nitrate. Also plant rotationally so you always have something using those nitrates or your levels may become harmful to fish. Plan your planting so your not harvesting too much in one big hit , scatter the timing of planting to maintain a balance of ammonia in vs nitrate out. IMO I'd also get you fish numbers down to around 800 max. ASAP.
    I've found it helps if you try and prioritise or production in the order :
    1) beneficial microbes
    2) plants
    3) fish
    The most important ingredient is your microbial culture, after all the bacteria and fungi you farm are what make aquaponics possible in the first place. Your microbial system is the engine that drives your garden and the rest must be sized to suit it or the system just won't balance.
    Cheers
    Hope that helps.
     

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