In the pics below you can see the three algaes I'm battling: GDA, Thread, and some green algae on the sand.
Thread Algae
You can't really see the thread algae directly. There's not great gobs of it. But in these pics you can see many plants with large pearling bubbles around their leaf edges. That's the tread algae pearling. It's hard to see the aglae. But it's there.
As some of you will know, I had a tank once that had this stuff as a pestilence of biblical proportions. So it DOES scare me and get my attention. But I've come to understand it too. At least in my tanks. This stuff arrives in high light, high current, when PO4 approached 2.0.
Lately my tank has been ripping through Phosphate, with all the new stem plants I have growing. So I've been dosing to a bit above 2.0 to keep it from getting too low during the day. This next week I'm going to reduce my PO4 dosing just a bit, and I'll bet dollars to doughnuts that this stuff will diminish. Or I could shut off my 2nd filter and pump combo. That would do it too. And finally, I can reduce my photoperiod. Bottom line, I've go options. I'm going to try the PO4 reduction first.
Green Algae on the Sand
I don't know what this stuff is. I've gotten it multiple times on this tank, and have been watching it closely. It has a BGA look to it once it get's going like in the pic below. Except that it's not blueish. The first time I saw it I hit it with Maracyn, and absolutely nothing happened to it so I manually removed it - siphon off affected sand, chlorox soak sand, rinse and return sand to tank. When in came back, I tried a higher dose of Maracyn. Seemed to make my GDA go away, but had no effect on this stuff.
I've noticed that when it starts - a few weeks after a manual cleaning - it starts by greening up large chunks of sand. Not the little normal sand grains mind you, but only on bigger stuff. In particular, I've got power sand that has worked it's way to the surface, and it ALWAYS hits that stuff first. Then the big sand grains, and finally spreads to normal sand grains.
It only grows on sand, where light hits it. Does not seem to spread to plants. So IMO it's one of the "silica" loving algaes - as is the thread alga I mentioned previously. Never had either in a tank without sand.
And BTW, it's already gone. Did another manual removal this morning. What a PITA. It will say away for a month or two. I just wish it would STAY gone. I gather heavy dosing of Excel can do it. But that's going to have to wait until I get the other algae taken care of. Don't want to change too many variables at once (again).
Green Dust Algae (GDA)
Boy, is this stuff my nemisis. Without this, my tank really would be low maintenance. But this stuff is like the freaking Energizer bunny, it just keeps going. Or maybe like Jason from Halloween, it keeps coming back. Doesn't matter what I do it seems.
If you've been following this thread you know that I recently made a number of changes that had an immediate and significant difference in this stuff. But now it's back. Not as bad as it had been before the recent changes, but bad enough. You can see 4 days worth in the pictures. So what has changed?
As I mentioned, I've increased my phosphates a bit. But kind of doubt that's it.
I stopped that Maracyn dosing. That could very well be it... the Maracyn knocked it back, and it just took awhile to get really cranking again.
The stem plants that were supposed to help don't seem to have made a difference. They have all doubled in size since I got them a couple of weeks ago. In one pic you can see the Rotalla wallichii pearling its brains out. It's hilarious how much pearling these plants are doing. All the stems are growing nicely. But they definately are not helping the GDA. At the rate they are growing in 3-4 weeks there will be no place for the discus to swim. It is officially a heavily planted tank now. And the GDA persists.
The only other stuff I changed recently - before the GDA receeded - was changes in my filtration. And that has not changed, but now it's back.
So it's looking like it must have been the Maracny that made the difference. But that stuff cost mucho denaro for a 180, so I'm going to try Travis' suggestion of reducing iron dosing. I'll going to stop my daily supplimental ECA (ADA Fe drops) dosing for a week, and see it that helps. If not, I'm going to try the Maracyn again. Not because I think that is a long term solution - I don't. But I am curious to know conclusively if that is what has caused it to temporarily receed for me (twice now).
As always, you can click these pics to get a close up if you need to see the scary algae up close.