What algae is this?

[ricardo48]

Hi.

Im still having some trouble with algae. Im overdosing seachem products and have good 30ppm co2 and 3.5 wpg.

Please see attached pics... any idea whats causing this on my sword leaves. My siamese algae eater aint touching it.

 

[kaiofcanada]

That is black spot algae. It is a form of red algae. I mostly grows on slow growing plants and long lived leaves like swords and anubias as well as rocks and such. The best way to keep it from spreading is to pinch off affected leaves.

You have likely noticed that it is impossible to rub or scratch off without damaging the leaves. Black spot grows when CO2 is low or inconsistent. Regulating CO2 better will help keep this in check.

Another more involved way to kill it will require that you use excel directly on the affected leaves. I did this, but ended up having to unroot my anubias to do it. The anubias came with black spots from a friend. I took a cotton swab and applied flourish excel directly on the leaves and then replanted. It took a good three weeks before the anubias showed any signs of growth again, which is common when uprooting a plant. If you choose this methods just be aware of that.

 

[ricardo48]

Ok Well it only seems to be on my sword at the moment and on some edges of my chainsword leaves. My co2 is a constant 25-40 ppm depending on time of day and im over dosing excel x5 almost every day.

 

[kaiofcanada]

Unless you have like 50 airstones and the craziest water circulation there is NO need to 5x dose your tank with excel and have injected CO2....not even if you have high light. Your tank is way too small for that need of CO2.

Just because you add more CO2 doesn't mean that the plants can use it all or that it won't itself cause nutrient imbalance. PLants will grow more aggresively and use up certain nutrients and cause a shift in the nutrient balance throughtout. Having considered your dosing, I would guess that black spot algae may in fact be caused by a nutrient imbalance as well as CO2.

You should be able to grow healthy plants simply with CO2 injection or excel dosing and high light. You do not need both. If you ask me you are making the nutrient balance required for healthy plant growth and prevention of algae more complicated.

Was there a reason you decided to dose and inject CO2 in the first place?

If it is only on your swords, I would remove the affected leaves and reconsider your dosing.

 

[ricardo48]

The excel overdose was to kill black beard algae which i have. i spot treatment 5 times the dose overwise it never kills it.

My dosing regime is based on the instructions on the seachem bottles. I have tried increasing and decreasing this with little change in results.