All Fish Died

Discussion in 'Fish' started by peterk, Dec 3, 2010.

  1. peterk

    peterk New Member

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    Tuesday I put duckweed from same pond , thats had no changes, I been using for a year. In small 3mo old system,~400 ltrs, it's been stable,pH only measurement I can make is ~7.5. Wed morning 6 dead fish, night 8 more, today only 1 left, very small 1, it's 1/2 dead. No visible symtoms, gills look ok, some floted to top, some on bottom. Put same duckweed in new larger system, ~ 6000 ltrs FP, none have died, eating well, this ystem is outside, we're on 2nd of 3 days of rain, so everything is diluted. Just got contract for all lettuce I can produce, so I need fish.
    No other changes. Intend to drain out old system, refill with water from new system. Ideas? Net access has recently become difficult so I won't be able check till tomorrow.
    Pete
     
  2. ian

    ian Member

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    The Duck Weed used all the available Dissolved Oxygen and the Small system couldn't replace it quick enough!
    Evidenced by the Biggest fish dying first (i.e. they need the most oxygen) and the smallest being the longest lasting.
    It was mostly OK in large tank because of simple volume of water and DO available, compared to the surface area of Duck Weed introduced.
    It is also obvious that you don't have enough surface agitation if you can grow DW in a fish tank(Duck Weed requires relatively calm water surface to grow in), that surface agitation gives you the water to air contact you need for oxygen to become dissolved for fishes use. Covering the surface with DW also limits the amount of surface contact available thus further lowering your DO.
    You may have aeration by using bubble generators (air stones, membranes etc. etc.) but these only work when they hit the surface of the water and create movement of that surface to increase atmospheric contact. The bubbles (big, little or otherwise) do nothing to increase the Dissolved Oxygen in the water. They are insignificant in surface area, don't stay in contact with the water long enough for any meaningfull transfer of O2 and they cannot supply enough O2 at any meanifull depth to be absorbed.
    If you have covered the surface of your tank, wholely or partially, with DW, then you also reduce the amount of surface agitation in your FT for any Oxygen transfer to take place.
    No brainer! Don't put DW in Fish Tanks!! You will kill your fish.
    Cheers IanK
     
  3. Castaway

    Castaway Senior Member

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    Your post Ian made me think about paddle wheels. Any info on them? Tips etc. DIY methods would be a good topic to cover...
     
  4. ian

    ian Member

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    Frank,
    This site info is a good source of info on paddle wheels etc.
    http://www.fish.wa.gov.au/docs/aq/aq020/index.php?0308

    I have opted for a simple venturi on the bypass loop from the fish tank pump for oxygenation. It supplies water and bubbles for agitation at the bottom of an 800mm deep megabin FT, disturbs any strata, agitates the surface and supplies the "swirling" action for solids concentration.
    It serves more than just one purpose (as a Paddle wheel does) has no moving mechanical parts to break down, makes use of the existing Pump and reticulation, is quiet and works efficiently.
    That is why I also opted for a Venturi as my 12V back up instead of air pumps/stones etc. The Power Stream venturi from Murray is a great little unit when hooked up the the 500GPH 12V Bilge pump, relay switch, 12v Battery and charger that gets tested every week, I wouldn't change a thing.
    Cheers IanK
     
  5. Castaway

    Castaway Senior Member

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    Excellent link. I was looking for something like that with diagrams. Even gives you a cost break down of electricity used etc.
     
  6. Wendy in BC

    Wendy in BC New Member

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    I was wondering why, when DO gets low and a the big ones go "fins up", why there isn't enough DO left to support the smaller ones. Do they all reach a point of no return together, regardless of size?
     
  7. kellenw

    kellenw Member

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    Hi Wendy,

    It's basically a chain reaction. As the fish die, this further depletes DO levels. Each successive death makes the situation worse.

    Having some zeolite and some hydrogen peroxide on hand for such emergencies can help to stave off disasters like this.

    Peter,

    Sorry to hear about the loss. That can really sting when you have a major fish kill. Don't feel too bad about it though. Virtually everyone has had a fish kill at one point or another. While it's unfortunate, it also tends to teach us valuable lessons.
     
    Last edited: Dec 3, 2010
  8. Wendy in BC

    Wendy in BC New Member

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    Thanks Peter,

    Do you dump in H2O2 as a source of quick O2, when you see dead fish?
     
  9. kellenw

    kellenw Member

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    Exactly.

    When dealing with hundreds or thousands of gallons of water, it's not really possible to do a "quick" water change, so if an ozone or oxygen system is outside of the budget (it is for the vast majority of us), the H2O2 is a good standby. An emergency agitator (a water paddle is one example) is a good piece of standby equipment to have as well. Of course, removal of dead fish as soon as humanly possible is also crucial.
     
  10. Wendy in BC

    Wendy in BC New Member

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    Peter,

    What sort of volume/volume of h2o2 would you add if you detected a problem?

    I don't suspect the standard pharmacy 3% h2o2 is sufficient, and 35% reagent grade (explosive) won't really work for a home system.

    I forgot to ask what zeolite was?
     
  11. kellenw

    kellenw Member

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    The ratio of H2O2 to water volume is a pretty heavily debated subject, and I have to admit I am in no way qualified to give you a definite answer on that. I have the benefit of ORP and DO meters... well HAD a DO meter until it went belly up, and I decided monitoring ORP only worked fine for me, at least for the time being. During a crash (haven't had one in a couple of years thank goodness), I would merely keep adding H2O2 until I saw ORP and/or DO stats improve to a reasonable level.

    Drug store grade 3% works just fine. You just have to use more of it, and as you mentioned it's safer to have around. Since it's pretty cheap stuff, not a big deal. One of the primary suppliers of the lab grade (35%) H2O2 to aquaculturists in the US also has a large sister company in Canada (Western Chemical). It is branded as Perox-Aid. I believe Western Chemical has "dosing" recommendations and full directions of use pdf's available on their website for the 35% stuff. You'd just need to recalculate for 3% if you wanted to use their dosing rates.

    (I'm Kellen by the way... Peter was the OP) :)
     
  12. Wendy in BC

    Wendy in BC New Member

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    Sorry Kellen in mistaking your name. Thanks so much for the info, I will do my "do dilligence "and research, you have definately given me a place to start.

    Might I ask? How hardy are tilapia with temp? I can't seem to find much info regarding this.
     
  13. kellenw

    kellenw Member

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    No Problem Wendy. Glad to help!

    I'd say start another thread on "tilapia temperature tolerance", so as to keep the threads on topic, and I'll be happy to add my two cents. :)
     
  14. Yabbies4me

    Yabbies4me Super Moderator Staff Member

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    Hi Kellen,

    What?... threads on topic!... here?... :(... Don't go setting a precedent!... you obviously don't know about Collingwood yet!

    But on a more serious note, in your experience, do you know what affect adding Peroxide to the FT will have on the beneficials? ie: is it okay up to a certain level?

    Cheers, Yabbies.
    .
     
  15. Wendy in BC

    Wendy in BC New Member

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    yabbies, I don't imagine it has any unwanted effects, it disacociates into o2 and h2o
     
  16. Wendy in BC

    Wendy in BC New Member

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    soory>>>not spell checking
     
  17. Yabbies4me

    Yabbies4me Super Moderator Staff Member

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    From a hydroponic website:

    It's how Hydrogen Peroxide breaks down into oxygen and water that worries me, it's my understanding that feeding on organics in the water is what causes Hydrogen Peroxide to break down.
    .
     
  18. kellenw

    kellenw Member

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    Too much H2O2 can "burn" gills and unprotected soft tissues. What "too much" is exactly, I'm not sure. :D

    Oh, and Wendy I forgot to answer what zeolite is. It is actually a group of aluminosilicate minerals.

    <geek hat on>
    Zeolites are volcanic minerals consisting of hydrated calcium, potassium, sodium aluminosilicates. What is important to us in aquaculture is that they provide a virtually "instant" solution for an ammonia spike. As water comes into contact with the zeolite it is held in channelways by absorption. The lattices are negatively charged, and they loosely hold positively charged cations such as calcium, sodium, potassium, and ammonium. This ability to exchange one cation for another is known as their “cation exchange capacity” (CEC). As soon as the ammonium ion is in the lattice it's not water soluble.
    <geek hat off>

    In short, zeolite chemically filters out the ammonia/ammonium. :)

    Zeolite is sold in small quantity (and extremely high prices) at pet stores. It is marketed as a charcoal replacement or addition. It looks like "white charcoal". Usually it is branded with a fancy name, but it's still just zeolite.
     
    Last edited: Dec 3, 2010
  19. RupertofOZ

    RupertofOZ New Member

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    And that's one reason why anyone with a home system should avoid using the stuff...

    And the other is, as noted... it is anti-bacterial....

    IMO... it has absolutely no place in aquaponic systems...

    If you system is oxygen depleted, and/or your fish are dead/dying... then your system is badly designed or seriously out of balance.

    From my "commercial" hydroponic days... I can tell you that hydrogen peroxide is hardly ever used to "oxygenate"... instead it's used almost universally .... to disinfect the channels/equipment... between crops, or after disease...

    Not entirely true... and the hint as to why is the phrase "losely hold positively charged cations"... it merely "binds" it....

    Certain pH levels... as typically found in AP systems... will result in dissassociation of any "bound" ammonia....

    And zeolite is only temporarily effective.... until it is "saturated"... after which it will NOT absorb any further ammonia...

    Yes you could use it as an emergency measure... and then dump the water....

    But you might just as well water change at the time... and it's more than likely that if your ammonia levels have spiked to the extent that you might consider zeolite.... that you almost certainly should water change anyway...

    Zeolite is only addressing the symptom... not the problem....

    I know I might annoy people.... but IMO... in your AP system...



    • Dont add any aquaria treatments
      Dont add any aquaculture treatments... unless you know exactly what you're attempting to do, why, and how
      Dont treat your fish tank as a science experiment or a test tube
      Dont add ANYTHING... unless you know what you're doing, why, how... and can observe any reaction... and know what to do if you get an adverse reaction
     
  20. Wendy in BC

    Wendy in BC New Member

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    well said John
     

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