I'm sticking to my guns and saying it high iron. I could very well be wrong, but everything points in that direction.Seeing how your using Eco and dossing CSM+B a little on the heavy side. All your other para's are great, if thier running constant.
I can't recall what I mixed my micro's at for dropping, it's been so long ago, since I mixed it. However I use Eco as well and only doss micro's once a week. Sometimes skipping a week.
When I had this problem a few weeks ago. It appeared this algae seamed to spread more with the lights off. I'd wake up in the morning at it appeared to have gotten longer and spread over night, while the lights were off. Have you noticed this by chance?
I agree with TG. Either remove the lighting siesta or shorten it. Let the plants fight it out with the algae. With 18ppm
CO2, one of thems going to win.
I run my planted Discus tank at 18
ppm CO2 a well. Probobly for the same reasons you do. To keep
PH swings to a minimum during
WC's and keep from having to trim plants every weekend.
Consider this. On your next
WC. Pick as much of the algae off as possible by hand. Do your routine 50%
WC. Afterwards only doss for Nitra and Phos accordingly. Don't add any Macro or Micro ferts. Observe for a couple of days and see if the algae receeds or atleast slows in growth rate (man this stuff grows, spreads fast). If you start seeing signs of plant yellowing, you might add some Pott and Mag, but I would'nt add any micros to this tank for 2 or 3 weeks.
Micros are just that, micro amounts. A small bit ocasionally, goes a long ways. Where as Macros need to be dossed in larger amounts and more often.
Oh, I almost forgot. I ran down to the
LFS and picked up a single bunch of floating stem plants as well, for 1.69$. I can't even tell you what species it is, all I wanted was something to help chew up nutrients. Within a week this crazy plant quadrupaled in size. Every week I have to toss 2/3's of it on the compost pile it grow so fast. If you feel its a high nutrient problem. Certainly worth tossing a couple of cheap floating stem plants into the tank to help chew up nutrients. Beats doing frequent
WC on a 125g Discuss tank 8O
I'm actually in the process of slowly piecing together a 120g Discus tank. I've pretty much decided a
UV filter for 80-100 bucks online, is a bargain when you consider how much you've already invested into an x large planted tank.
Keep us posted. This is a great post for future reference.