week 3: red Cyano outbreak still strong

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This topic contains 3 replies, has 2 voices, and was last updated by  Simon Ma 8 years, 1 month ago.

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    Simon Ma

    Hi all,

    relocated an existing tank to a new home, changed the sand bed and decided to try Nualgi. I had very minimum algae/cyano problems to start with but nitrates and phosphates were sometimes a little high.

    Tank overview:

    4ft tank, 422L with additional 100L (or more) sump

    protein skimmer, refugium with chaeto, bio pellets, chiller

    Temperature: 26-27 deg Celsius

    fish and LPS reef tank

    Start dosage: 3ml per week.

    <span style=”text-decoration: underline;”>1st week: Cyano outbreak:</span>

    After my first dose, I had serious outbreak of red cyano. Sandbed was covered in a layer of slime, corals were not extending fully. strands of cyano were all over my corals. Currently spending alot of time syphoning out the slime.

    <span style=”text-decoration: underline;”>3rd week:</span><span style=”text-decoration: underline;”> Cyano still uncleared:</span>

    Have increased my dosage to 4ml per week this week. Cyano is still raging. Still doing weekly water changes. Nitrates and PO4 are dropping (since the algae and bacteria are so active)

    Some corals are not looking too healthy (polyps not extending, colour not radiant, even early signs of bleaching) but have improved since my water change 2 days ago (still monitoring, might or might not be linked to Nualgi)

    I will update again after my next dosing.


    Question: Is it normal to have such serious cyano outbreak even after 3 weeks? And anyone having these problems and how long does it take for your tank to clear? Even with regular water changes and removal of slime. It is quite worrying and I contemplated stopping after my second dose – since I didnt have any such problems to begin with.



    We know that there are a lot of trapped nutrients in reef tanks in the rock and substrate. Nualgi by itself does not have any significant nutrients to cause algae/cyano. So it is some amount of pain but once the nutrients are purged, the tank will be much healthier. Here’s an example of feedback received from another user last week.
    I had a very severe hair algae problem. Here’s what I did:

    1) Fixed problems with filtration (carbon and phosphate reactors had improper flow)
    2) Began manually removing the hair algae
    3) Stepped up water change frequency
    4) Started with Nualgi

    After 6 weeks I was seeing less new growth of hair algae, and it was getting easier to remove hair algae, but I was still behind the curve.

    5) 3 days of darkness for the tank
    6) More manual removal
    7) Continue with Nualgi

    I’m now close to declaring victory. There is still hair algae present, but is in very small amounts. There are small patches of cyano as well. Thus I’m not ready to declare victory just yet, but corals are growing again and the tank looks much, much better. I see light at the end of the tunnel.

    Nualgi was a part of the solution, and will continue to use it.
    Also, you may want to look at the issue of phenolic compounds in your tank which inhibit diatom growth. Here’s a good article on that http://reefdreams.de/lang_eng/info_12_eng.html
    If you take a sample of your tank water in a white bowl and compare it with water going into the tank you should be able to tell if this is an issue. The water in the tank will be yellower with fish odour.


    Simon Ma

    Hi Nualgi Aquarium,

    Thanks for the feedback

    Today the tank seems to have more hair algae and not much Cyano (red slime) patches. I shall take that as a positive sign that at least one of them seems to be dying down. Either that or my daily removal of slime that gets caught on the rocks and corals are helping.

    I did a simple check of my tank water. It is clear without any tint. At least I have one less problem. 🙂

    I shall soldier on and update next week.



    Simon Ma

    Hi all,
    Week 6:
    Some updates on the tank after another 3 weeks.

    Dose: increased to 4ml instead of 3ml for last 3 weeks.
    1.On week 4 and 5, I performed siphon of the sand bed, rocks and corals 2x a week.
    2.weekly water change of 25 to 30%.
    3.lighting, feeding, dosing remaining constant
    4.current week 6: no extra siphon of the tank other than during water change

    1.Nitrates and Phosphates are at 0 with API test kits.
    2.red slime has mainly cleared at week 6
    3.sandbed and rocks are covered with brown algae which Tangs graze on. I assume its diatoms
    4.some green algae remains but only 5%
    5.water clarity has improved significantly

    I shall continue the same dosing and update in 2 weeks. The tank is still very heavily covered in algae, except now it is brown and does not cloud the water. It also does not form strings/strands. I still do not see pods other than in my refugium.

    Red slime has mostly cleared – except on my fan coral. Any suggestions on how to clean the fan without damaging it?

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