Can't seem to get rid of GSA

Discussion in 'Algae' started by flygja, 7 Oct 2009.

  1. flygja

    flygja Member

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    Hey guys, hope you can help me out here. Firstly, a picture of my tank and its specs.
    _DSC6501_dxo_raw_gimp_600.jpg

    90cm x 45cm x 45cm ~140 litres
    Filtered with an Eheim 2215 and a Tetratec EX90
    Lit with 4x 36W Philips 865 6500K fluorescent lights with reflectors 8 hours per day
    Injected with pressurised CO2 via 2 inline reactors at 2-3 bps
    Base is ADA Amazonia II with Shirui decorative sand
    Fertilised with EI:
    6g KNO3
    0.7g K2SO4
    5.1g KH2PO4
    15.5g MgSO4
    Those are the weekly doses, I dilute 3x the amount in 250mL of water and dose 10mL per day which results in 20ppm NO3, 30ppm K, 9ppm PO4 and 10ppm Mg per week
    Traces and iron through 4mL of Seachem Flourish per day which is roughly 0.5ppm Fe per week
    50% water changes once a week

    I have raised the PO4 dosing from 3ppm weekly to 6ppm weekly to 9ppm weekly now but the GSA just shrugs it off. It's even occurring in areas with pretty good flow like on the larger rocks in front and on the white decorative sand. You can just about see it in the photo above, but its gotten worse since I took that photo a few weeks ago. I use a permanent JBL CO2 checker just as a gauge of CO2 levels and its yellow in all parts of the tank where the GSA live.

    I blacked out the tank before previously and it does remove most of the GSA but it just bounces back again. I wanna tackle the rootcause rather than the symptoms. Do you guys see anything wrong with what I'm doing?
     
  2. Dolly Sprint 16v

    Dolly Sprint 16v Member

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    I would say its down to your lighting period being to long especially using all (4) tube at once - try 8 hrs @ 2 tubes with a mid day boost of other 2 tubes for 2 - 3 hours. You stated that you increased Po4 and that did not work so I would go back to original dosing - any way have a look at the attached short cut:-

    http://www.thetropicaltank.co.uk/phpBB/ ... bdd6bd0906

    Regards
    paul.
     
  3. ceg4048

    ceg4048 Expert/Global Moderator Staff Member

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    Hi,
    Loveley rockwork. GSA is both CO2 and PO4 related. If the PO4 increase hasn't helped, then try upping the CO2. That's a huge amount of light over a 35G tank. Some of the slower growing plants like Anubias are susceptible to GSA under high lighting. The easiest thing to do might be to lower the lighting if you are already maxed out on CO2.

    Cheers,
     
  4. flygja

    flygja Member

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    Thanks for the advice guys. I *think* I have enough CO2 based on observations and the drop checker. I'll have a go at modifying the lighting duration and see how that goes.

    Another question I have is, will tweaking the CO2 + PO4 + lighting kill existing GSA? I don't want to remove the rocks to bleach because it plays havoc on my substrates. Blacking out is one of the other options too.
     
  5. Dolly Sprint 16v

    Dolly Sprint 16v Member

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    Its just a case of getting the right balance between fertz / lighting / Co2 - hit the sweet spot and you are laughing.

    Regards
    Paul.
     
  6. ceg4048

    ceg4048 Expert/Global Moderator Staff Member

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    Well your GSA doesn't think so...

    Typically no. It's very difficult to keep algae off of non-growing surfaces. It's not clear whether you were talking about having the algae on rocks only or on plants as well. Under high lighting it's almost inevitable that you will get some algae on rocks/wood.

    It's not necessary to remove the rocks. You can dip a toothbrush in Excel and scrub during a water change, for example.

    Cheers,
     
  7. Mark Evans

    Mark Evans Expert

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    unless you hit the sweet spot. my 60 was spotless, literally. even with wood, stone and anubias in full sun, everything stayed clean. i do feel that light plays just as much a vital part as co2. even with high co2, the light height is where you control everything.
     
  8. flygja

    flygja Member

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    Hey Mark, I remember a post you made in your 60's journal, where you had some GSA on the Anubias, and you increased the PO4 way above normal and raised the MH lighting and it was gone within a few weeks. That statement really is my holy grail right now!

    Anyway, I'm gonna try a 4 or 5 day blackout and see if I can control the GSA through lighting period after that. Right now its extremely stubbornly stuck on rocks and plants and white sand.
     
  9. Mark Evans

    Mark Evans Expert

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    yep, 1 week. But i don't think the po4 increase alone would do it. If EI dosing is correct there should be enough po4 to prevent GSA (i think) it was the light height that seem to cure it. CO2 was already high, believe me and flow was extreme.

    i did add more po4 purely out of hearing this suggestion, once the distance of the light/tank was increased, it went and the light stayed at that height.
     
  10. vauxhallmark

    vauxhallmark Member

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    Haven't got a solution to your problem, but just wanted to say what a great looking tank that is - I love it!

    Mark
     
  11. flygja

    flygja Member

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    Mark, just to confirm, when you added the extra PO4, did it kill existing GSA? Or did you manually removed all traces of GSA and increasing PO4 caused it to stay away?

    Mark (VXR version :D ), thanks for the comments. Its a nightmare trying to keep it clean at the moment.
     

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