Cyanobacteria - how to control it.

[falcon]

I've read somewhere that cyanobacteria can be caused by high phosphates and high light. Is this true. I have been battling it for a couple of months and most of it had disappeared but some still remains and grows on tips of vals and driftwood. I just can't get rid of it. Should I try and reduce my phosphate dosing? Currently I am dosing 0.75ml of enema 4x/wk with KNO3. The tanks is 65g 36x18x24, pc lights 2x96w.

Or should I give it more time. I have been increasing my co2 over the past week. Not sure what that will do. Maybe I should turn off one of the tubes? One benefit of using higher phosphates is that I haven't seen the spot algea on the glass in a week.

Thanks.

[Timmain42]

Okay, here's what Tom Barr would say:

It's a lack of nitrAtes. Dose a full dose of nitrAtes for your tank, according to the Fert Sticky at the top of this Forum. Completely blackout your tank for three days. Do a 50% water change. Dose the full dose of nitrAtes again. Keep an eye out on your levels to ensure this doesn't happen again. Grow the plants well and the algae is retarded.

I didn't believe it either, 'til I had a huge outbreak of BGA and could NOT get it under control. Tried Tom's method, have never had major issues with BGA again. :shrug:

[falcon]

Timmain, I am currently dosing 4.5g of KNO3 at w/c 3.5 two days later, 3.5 two days later, and 3.5 two days later. So, I'm dosing 1x4.5g and 3x3.5g - is it still not enough? When I'm dosing 4.5g at w/c, I'm adding about 13.25ppm of NO3.

Please let me know if my dosing is sufficient if not, I will increase it. This tank has been especially difficult to control as the light are high intensity 2x96w pc lights for a 24" tall tank.

Thanks.

Edit: actually I am dosing 1.5ml 1x at w/c plus 0.75ml 3x/wk fleet enema.

[Timmain42]

I don't know if it's sufficient or not, how much water does your tank actually currently hold?

[falcon]

I'd say about 58g.

[RTR]

And what are the nitrate readings in the tank pre- and post-dosage? You don't have to test routinely using Tom's Estimative Index, but you do need to do a little testing to be sure you are in the right ballpark.