Cyano in lightly planted tank.

[mooman]

Most of the old threads on this topic talk about ferts and nutrient imbalances. Messing with that stuff really isn't my bag and since the tank I'm concerned with is low light (29g with two 18w lights) and lightly planted (Java moss, java fern, octopus plant) I guess I need some additional advice

Aside from the cyano the tank has always looked great. It has been up for about nine months. I do weekly 30-40% water changes. Nitrates sit at about 10ppm (my tap water contains 5ppm). The little algea growth I've seen is quickly scarfed up by otos and rubberpleco. Tank also contains one med angel, 5 hatchets, and 2 apistos. I feed very little. I recently moved and took the oportunity to change over to sand. Two days after the move I noticed a small spot of cyano on the sand. I know about blackouts, antibiotics, more plants (I will add more soon) and increased circulation (the tank has one of those eclipse hoods and if anything has too much circulation). What else can I do to treat the problem and not just the symptom? Could the fact that the lights are reaching the end of thier life be a factor? I don't want to start worring too much about nutrient imbalances, but will if I have to.

Help me plant geeks.

[knashash]

I have been battling this stuff for a while in my 10 gallon tank. I tried three blackouts on the tank for a minimum of 3 days at a time and although it definatley helped...the Cyno came back every time. The last thing I tried a couple weeks ago seems to have worked. I did a thourough manual cleaning including the filter and used chemicals. Many people will advise you against this but I was frustrated and needed to try something else. I used one capful of liquid algae destroyer. After a couple days I did another cleaning and water change. I have not seen signs of any Cyno since. So take my experiences for what its worth, but that Cyno is very stubborn stuff. I would say its easy to clean up...but very difficult to eradicate. Again most people on this forum are staunchly anti-chemicals.....but it was the only thing that worked for me.

Oh and I should also add...that I spent a good amount of time getting my tank in Balance as well. Got my N-P-K Ratio right and had good C02 levels...it still came back.

I will say that under low light conditions, one natural thing you could do is inject C02.....can only help your situation.

[reiverix]

A cleanup followed by a three day blackout, then dosing KNO3 should do the trick. I can induce BGA in my tanks by letting nitrate drop below 10ppm. Columbus water can be a bit troublesome to work with.

[LimnoMan]

I would think that it could be the light. Cyanos have evolved to take advantage of wavelengths of light that are ont generally used by higher plants. They can take advantage of green light. I'm not sure which kind of bulb would emit light the cyanos use but I think it could be a problem.

[happychem]

I'm with Reiverix. Halifax water is nigh perfect as far as I'm concerned, but when I get slack with KNO3 dosing and a little liberal with the PO4 and K I tend to get BGA, just cleaned some out of my 18 gal yesterday, this was months after the last time I had any - and did a 3 day blackout.

I would be one of those staunchly anti-chemical types ;) , ironic given my life's work... I'm all for adding something that solves the problem, but, IMO, anti-biotics and algae killers only treat the symptoms.

The easiest way to solve your problem - if it's just a little bit of BGA - is to clean off what you can and add some KNO3. For your 29g tank mix 3 tbsp. of KNO3 in 250mL of water. Add 10-15 mL of this solution to your tank after a 50% water change and cleaning. This should stop it from growing and help the plants to outcompete the algae. If the bloom gets the upper hand, do a big cleaning and a 3-4 full day blackout followed by another 50% water change and 10-15 mL of the KNO3 solution.

Cyano will come back if you let NO3 dip, or in my experience, if the N:P ratio gets much smaller than 10:1 - in other words, if you've got lots of PO4, but this is just my take on BGA and I'm by no means an expert.

[mooman]

Thanks guys, you have once again come through for me. Your advice seems to echo the general consensus on bg algae control that I got from reading old posts on thekrib and Plantgeek.net (at least the posts made by people that had a clue). It seems that the problem is kinda misunderstood. Thanks again.