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Cloudy water a good indicator?

Discussion in 'Estimative Index' started by scottward, Feb 14, 2013.

  1. scottward

    scottward Guru Class Expert

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    Hi Guys,

    Now that I have a UV hooked up (and for the moment I am running it 24/7 but will step this down at some point), there is no doubt that when I dose additional iron the water turns cloudy.

    And, not suprisingly, cloudiness is proportional to just how much extra iron I dose.

    Just wondering, is this cloudiness actually a good indicator that I've dosed enough iron?

    In other words, would it be a good idea to slowly back off the amount that I dose until the cloudiness stops and then I'll know that I've hit the "sweet spot"? If I dose any more than this sweet spot, the extra iron floating about that the plants don't grab will go cloudy (and if it goes cloudy it's going to waste anyway I believe)?

    Bio a while back you helped me "concoct" a 13% EDTA iron mix. I've been mixing up 2 tablespoons per 500mls and dosing 30mls 3x per week. I never bothered to reduce this dosing to see what would happen, it was so easy to mix it up, so cheap, that I just dosed it anyway.

    Possibly there is enough DTPA in the Rexolin APN micro mix that I mixed up anyway. If I just does the Rexolin mix and forego the additional iron, the water does not cloud at all.

    Scott.
     
  2. Tom Barr

    Tom Barr Founder
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    I'd not run the UV.

    Maybe for a few days once a month if you feel like it.
     
  3. scottward

    scottward Guru Class Expert

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    I run the UV for the fishies. I will step it down soon with some experimentation.

    Back to my question though.......well?

    Scott.
     
  4. Biollante

    Biollante Lifetime Charter Member
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    Sorry Been Busy Feeling Sorry For Myself

    Hi Scott,

    Sorry I do not recall the details and I cannot seem to locate the thread, if you can help me out, I may be able to give a better answer. :)

    Anyway, the cloudy water with the addition of iron, not cloudy without seems a like a strong suggestion you may be correct about the UV and the iron.

    • I have heard others say the UV was removing iron; perhaps oxidizing it, I have not seen this.

    I have set up a couple of containers with UV and high iron, I should be able to get a couple more going this evening or tomorrow.

    I am going to have to do a bit of research and get back to you. ;)

    The biggest problem I have seen is staining hence a reduction in UV efficiency, this occurred in a system I was running growing a bunch of sword plants, I seem to recall the water was around 1-ppm iron. Being Echinodorus spp. I was mainly root feeding so; the high iron in the water column was incidental.

    I just saw a manufacturer warning against iron over 0.3-ppm reducing UV-sterilizer efficiency.

    I can’t find anything reliable on iron removal via UV or any other light. I wonder if the UV-light, the DPTA, iron and perhaps something else in the water is reacting.

    This almost sounds like sunlight breaking the chlorine-chlorine bond, I wonder if your UV setup has enough energy to break some chemical bond, perhaps the chelating agent. :eek:

    What kind of flow rate are you getting through your setup?:confused:

    Have you removed a glass of water when cloudy and just let it set?

    • If so does it clear?
      • How long?
    • Assuming it clears, can you see crap (precipitate) on the bottom?
    • Assuming crap (precipitate) on the bottom, what happens when you drop in a magnet?
    :gw
    Biollante
     
  5. DaBub

    DaBub Guru Class Expert

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    Bio could this be ozone?
     
  6. DaBub

    DaBub Guru Class Expert

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    bio Could the uv be creating ozone?
    I looked it up, Fe(II) is oxidized to Fe(III) by ozone
    And Fe(III) is hydrolyzed to Fe(OH3)
    And precipitates out.

    Isn't this what you got a couple of years ago with that O3 generator?
     
  7. Biollante

    Biollante Lifetime Charter Member
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    Hmmm... Not At All Sure I Understand...

    Hi DaBub, Scott, All,

    While I do not think the UV-lamp is producing ozone, I have seen enough credible reports as Scotts, especially around DTPA, I am simply not experienced enough to know how much energy is required to break the ligand bonds. I would have guessed this more likely to be a problem with iron chelated with gluconate then DTPA. Particularly with the low-pressure UV lamps we use.
    :eek:

    Hmmmm…
    ;)

    I have not been able to track down a study; apparently, an Israeli study found UV degradation greatest in Fe-DTPA, less with Fe-Na-EDTA, and least with Fe-EDDHA.

    I just found a letter attributed to Dr. Lynette Morgan (well-known hydroponics person) citing Runia, 1992 for a 33-55% reduction in Fe-DTPA at a 24 to 28-[SUP] MJ[/SUP]/[SUB]cm²[/SUB] dose and 92% reduction in Fe-DTPA with a 277-[SUP]MJ[/SUP]/[SUB]cm²[/SUB] dose. These are from high-pressure lamps.

    Dr. Lynette Morgan cites Runia, 1993 saying with low-pressure lamps at 250-[SUP]MJ[/SUP]/[SUB]cm²[/SUB] the rate of Fe-DTPA destruction was 20-40%.

    DaBub (a research wizard), or anyone, would you be kind enough to track down these studies?

    Scott, assuming this is accurate; you will probably find a lot of gunk on your lamp sleeve, meaning the lamp is increasingly less effective.

    Next, it may be that reducing the dwell-time may lessen the iron lost. If you are losing iron then you must be losing manganese and probably molybdenum.

    The good news is that it appears you would not be losing more than 40% iron, at least 60% remaining available, so if you have a specific target add 40% more or start using the UV-sterilizer, part time, dose in the morning run the UV overnight, for instance.

    Biollante
     
  8. DaBub

    DaBub Guru Class Expert

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    I will try!

    I may have found it, check email
     
  9. Biollante

    Biollante Lifetime Charter Member
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    Appears You Hit the Jackpot!

    Hi DaBub,

    Thanks! :cool:

    Biollante
     
  10. scottward

    scottward Guru Class Expert

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    Hi guys,

    Bio, thread about DIY micros + separate iron is here http://www.barrreport.com/showthread.php/8885-Make-my-own-trace-mix

    I'm using a TMC Vecton 600 and I'm pumping about 600lph through it. I think I'm hitting it pretty hard given its a 25 watt bulb, I'm using a slow flow rate, yet still turning the tank over 1.5x per hour.

    I noticed some slight whitening of the echinodorus tenellus leaves, but I've seen that before due to a slight drop off in CO2. So I bumped the co2 up a bit.

    So other than a little cloudiness, everything seems to be growing ok.

    Taking a glass full out would be interesting to try, I will try it if it clouds up badly again.

    What I'm thinking of doing is running the uv from 8am to 8pm, as I usually dose my tank at night after 8pm. This way, the dosed nutrients have got 12 hours to absorb all they need. If when the uv comes on at 8am there is some minor cloudiness so be it, I guess the plants didn't need this iron anyway.

    Plants can store iron can they not? Or is iron one of those nutrients that plants cannot store/move about internally such that a ready supply should always be available?

    Bio, what are your thoughts on bacterial control when not running a uv 24/7 ?

    If the uv is spending say 12 hours nuking something, only to then be turned off for 12 hours, will that 12 hours off be enough for said nasty to multiply and gain the upper hand all of again? I guess knowing what the fastest, nastiest bacteria that could be treated with uv is capable of reproducing at at our temperatures and making sure the uv is on sufficiently long to handle the worse case scenario?

    Sorry if this is a bit disjointed.

    Scott.
     
  11. scottward

    scottward Guru Class Expert

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    Hi Guys,

    Any further thoughts/updates?

    An observation - I've noticed that the leaves on my E.Tenellus has been growing in a bit pale, turning a bit white.

    Hmmmm.

    Iron deficiency or good old CO2 once again?

    No brown spots or problems with H.Polysperma (apart from the ongoing but seemingly harmless nyctinasty)....if there was a CO2 problem I would expect this plant to show a problem first, but it's not.....

    I think I will switch to 12 hours ON, 12 hours OFF with my UV, and dose just after the UV turns off so that the plants have a full 12 hours to soak up the nutes and see what happens.

    IIRC, plants will soak up nutrients equally well in total darkness as they would during the photoperiod.....yah?

    Scott.
     
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