More lumens - Suspicious Emergency Rooms

I should soon receive a new set of two 36" dual striplights for my
180 gal. tank, which will go with the existing four VHO driven
full-spectrum lights. Today I found and bought four CW T8s (no
daylight available in 36" size) with two Magnetek ballasts for them,
which I will use to upgrade the light strips.
I would like to hear comments and suggestions on the following:

1) I am planning to set the new lights on a separate timer, in order
to increase the light input only very gradually to attempt to
minimize initial algae blooms. Would 3-4 hours be a good starting
point, with gradual  2 hour increases based on the plant and algae
growth response? In alternative, I can start installing two tubes
only (for ~8 hours/day), adding the other two later. 

2) After a decrease probably related to very intensive water
changes, the chronically elevated PO4 levels in my tank raised again
to 3 mg/l since when I resumed my normal water change cycles (~15%
at least twice a week). However, the NO3 levels are at their
historical low (3 mg/l). I currently have no visible hair algae, and
almost no cyanobacteria.  I was very surprised of these findings:
the only explanation I thought is that the regular use of PMDD has
stimulated the plants to take up more nitrogen, which limits algae
growth. However, a light limiting factor, possibly associated with
residuals from the phosphate-rich fertilizing tablets I used quite a
while ago, has not yet put the plants in the condition of achieving
a better growth and a better phosphate uptake. Does it make sense?
Any implications on my plan to increase light levels?

3) I am not planning to change my 11 month-old VHO bulbs now that I
am about to put a lot more light in.  I will replace them only after
I will be able to keep all lights on for ~12 hours/day with no algae

I would guess that the alternative option would be to throw in
immediately all the new lumens available, ignore a probable algal
bloom, and give the plants all the possible energy to be competitive
as soon as possible. Anyone in favor of that?  Thanks to everyone
who will reply.

dionigi.maladorno at roche_com

PS Anubi (Italian spelling, I do not know exactly the English one)
was the Egyptian god of the dead. He was son of Osiris. Quite a nice
guy, with jackal head and human body. He used to ship the souls of
the dead to their final destination, which was chosen testing with a
scale if their sins were heavier than a feather....
This would lead me to think that the sign that one of the
subscribers saw in a hospital emergency room referred to something
else (or was a joke), but, just in case, I would stay clear of that
place... just as a patient, of course.