My plants practically effervesce and the only phosphate
inputs are less than 1g/day food @1.3% P Min.; and 0.25 ppm
(below the bottom 0.25 test chip, but not zero) in my tap
water (A 5g/day change goes into a 135G tank).

I use PMDD. The tank is fairly well planted (12 odd
species; 3-4 4" pots of each; 8 6" Swords; a mass of java
fern the size of a basketball; a good chunk of floating
Hornwort).

If you are serious about your plant tank's good looks, you
need to come to grips with a proper, long term, nutrient
regimen. Algae is bad, and adding stuff (including P) at
random until you get it is also bad.

Algae is a plant, after all, so you're always walking a fine
line.

I recommend PMDD (Poor Man's Dupla Drops). At least they
offer a prescription regimen. They give you a basic recipe
and how to conduct a proper, test based, tuning of that
recipe for your tank's unique situation; and proper dosing
control. Yea, you have to buy an suitable "pass/fail" Fe
test; you already have the nitrate. Mail Order works.

If you dose P, and you might have to if you have 0 P in your
tap and not enough fish to feed, then a PO4 test may be good
to have too. My tank always read dead clear (no
indication), so it was rather a boring waste of $10.

************************
BobWu wrote:
Hi folks, I planted my new tank last Friday. Friday and Saturday I saw
a lot of "pearling" on glosso, but starting from Sunday, no more (not
less, but absolutely nothing). I did not adjust lighting, or CO2
injecting (carbon plus running at 80%). Is it possible that my tank is
running short of nutrients? Or maybe it takes sometime for the plants
to settle first? FYI, my tank is 75G and nitrate=15ppm, I do not have
phosphate test kit, it is not easily available unless I go online. I
kind of suspect the lack of phosphate is the cause, since I did not
see any algae problem either.