I was wondering who has had in the past or has 3 watts or more per gallon and what problems have you had that you could not eliminate, such as algae that was solved when you lowered your wattage over your tank.
Jag,
With your 3.3 wpg, what's your photoperiod?
In my 45g I've had all sorts of problems over it's lifetime.
My biggest problem was this weird stuff that was like a cross between thread/fuzz algae and diatoms. It was like brown polyfil that grew 4-5 inches per day if left alone. I physically removed as much as I could, did a large water change, then a 4 day blackout, followed by another water change. At that point I also adjusted lights to 1x96w for 9 hours, 2x96w for a 4.5 hour burst in the middle. Brown nasty stuff never came back.
Traditional thread/fuzz occurred for me when my photoperiod was too long(typically when a timer would fail and I'd be out of town or something). Even at lower lighting(the 1x96w) if the photoperiod was too long, I'd start to see thread/fuzz....usually my first indicator that something was wrong with my timer.
Even at the customized photoperiod BBA, GSA, and GDA were also a minor problem.
All of the above was originally using classic EI(no modifications) and then later PPS-Pro (unmodified). I do not test my water. I perform water changes rarely. Usually it's a top-off weekly or semi-weekly (in my open top tanks) or biweekly(in the covered 45g), with a 50% WC every 4-5 weeks.
The ultimate solution is what I have now. Full intensity, 2x96w over a 45g, for 6 hours a day.
Growth of Ludwigia repens and hygro sp is still crazy, trimming once a week. Rotala rotundfolia and macrandra is a little slower, but it's actually better growth, not as leggy. Blyxa japonica is growing slower but more compact, which is really awesome. Needle leaf java fern is EXPLODING. Lobelia cardinalis has slow growth. Red Tiger Lotus is also exploding. I've produced two new plants in the last two months.
To be fair, this is in my 45g tank, which is my longest running tank, so it's really well settled in. The 46g was recently heavily modified(as you know) so it's still have some algae issues as part of the adjustment phase. The new-ish 75g has a bit of string algae here and there, but again that's settling in.
I strongly feel that if you reduce your photoperiod you'll see a lot of these issues go away. Maybe even do a blackout for 2 days, then come back with the modified schedule, just to give it a headstart.