What algae is this.

[terran2k]

What type of algae is this? and what causes it?

Tank is a 30gallon, single t5ho 39w, pressurized co2, dosing ferts.

[The Trigger]

Looks like black brush algae aka bba. Usually caused by low or fluctuating co2 levels and possibly low flow/dead spot. You can spot treat it with Excel or hydrogen peroxide to kill it, but if the underlying problem isn't fixed it will just come right back.

[Postal Penguin]

I agree. Cut those leaves off and fix the underlying cause new leaves will grow quickly.

[terran2k]

repositioned my spray bar from the back to the right side, i had to take one segment off since the side of tank is shorter in lenght, which increased the water spray pressure. think it might be too much for my fish...
but water now is going from right to left, spray bar on the top right, intake on the bottom left.

co2 comes on and off with the light as the solenoid is on the a dual socket timer with the light. is that good or bad?

i also do a 50% water change every week.

[Kathyy]

I have my CO2 on a separate timer and CO2 goes on before lights go on and off before lights out. Otherwise CO2 isn't at a good level when the plants are ready to take it in.

[The Trigger]

That method works great. My co2 goes on an hour before the lights come on and by that time the water is pretty well saturated with good co2 levels. Plants start pearling 2 hours after the lights come on