Thanks for the input Bert! It's a few good data points from which to try to draw conclusions from. If I'm reading it right, it doesn't sound like ambient sunlight is a significant factor, nor is overall level of light. But photo period and excess micros might be. And for you, the "let it grow through the life-cycle" thing made no difference.
Thanks. That's information to meditate on for a while... Please correct me if I missed something.
My records seem indicate that my photo period change had no impact on things though. I went back and checked. So I cannot explain why our observations contradict.
And your observations agree with Brilliant's. Not sure why mine seems to be different.
But I can say that my GDA is in major retreat right now!
I just got finished cleaning the tank walls, and there was virtually none to be found. A few tiny spots that I had clearly missed in prior cleanings, but the walls themselves were clean. Now, I had cleaned the walls two days ago. But it's been weeks since I could go two days and see no visible GDA grow.
So what has changed?
1) I dropped in all the stem plants I mentioned previously.
2) I've been dosing Maracyn daily. I'm on day 5 of a 7 day treatment.
3) I installed the new Ocean Clear 340 plus a new Pump to push it. So that means I'm pushing an addtional 250 (approx) GPH of water through the tank (new pump at 500+ vs. Eheim Pro II at 250) and that I pulled out a mature biofilter, with clogged mechanical filtration, and replaced it with fresh mechanical filtration and with zero biological filtration (it's brand new)
4) I replaced my "new" micron filter on the original Ocean Clear 340 (because its flow had eroded down to a trickle and pressure had climbed to 10 psi!). The replacement filter was actually an old one that I had blasted in Chlorox for days. In the process of doing that I found that my filter's outlet at the bottom had become clogged with grunge. So replacing the filter itself may have had no difference. But my flow rate through it (with the grunge cleared out) probably improved my flow from something like 100 gph to around 350 gph. Big difference.
So... can I say what has made the difference? Absolutely not. But things seem to be massively improved. It looks so good, that I'll be really surprised if things don't still look good in a week. (He says with fingers crossed.)
Sorry that I went and changed multiple factors at once. So there is no one thing we can point to if this works. But I was getting desperate. Sorry. It was getting to be a real problem. And for someone that has had real algae problems before, I was not going to let it happen again.
I guess we'll see in a week if it makes any difference!