Please help me identify the cause of this symptom

[Patrice]

What is this algae or this reaction and what is causing it. its killing my plants. My grass stop growing.




Here my setup
Alternative days, in the morning, ferts and iron
20 ppm nitrate
.5ppm phosphate
120 ppm magnesium
30 ppm calcium
0.1 iron (more or less)
c02 injection all day and night at 6.7ph initial 7.2ph
air bubble at night
2x 36w 6500 (removed deflector and added flowing plants to lower the light.)
9 hours light.
30 gallons tanks
Very low water movement on top
plants: moss, (stunt) Micro Sword (Lilaeopsis Brasiliensis) , java fern and Ludwigia Needle Leaf (Ludwigia arcuata)

 

[Patrice]

I stop adding iron for a week to see if its iron phosphate. I am still seeing expansionof this black dust or diatom or algae. Whatever it is, my plants are having problem. At high direct light its a reddish brown color. Both its not bba. Maybe excel is causing it, or magnesium. I don't know. Anyone?

 

[Patrice]

I am hearing that hydrogen peroxite can remove it. But what his the reason to have this problem in the first place?

 

[reefdiver]

Not really sure but it may be too much light and or the water movement.

 

[Rivercats]

Excel don't cause algae. In fact overdosing, which is not recommended will kill certain types of algae. Sometimes low phosphate contributes to Green Spot Algae. What type of iron do you dose? Liquid, like in Flourish Iron or Iron Chelate? .1 is not high iron. Increased surface water will facilate better oxygen/gas exchange which is good for fish. Water circulation in the tank brings nutrients to plants. You might want to increase circulation on the surface (you should have gentle ripples) and decrease light. Sometimes you have to play with how much light your plants really need. I just decreased my 3x150watt HID Metal Halides down to 6 hours and leave the 3x39watt T5HO lights on for 12. I have a 220 just to clairify. What type of fertilizers do you use? Liquid or Dry ferts? Dry fertilizers are much more economical to use. Look up dosing PPS-Pro method. It's very easy and economical. Hope this helps.