Thanks for the reply Tom. Just another of quick questions/comments:

2. You certainly don't have to, but with the responses I've gotten for
the last 10 years, you can test and chase nutrients with test kits if
you want, depends on how much algae and how you want the tank to look.
Some don't mind a little algae and not do their water changes or don't
have plants that nearly as picky.

That'd be me, in that I would like an algae-free tank, but time constraints
limit what I can do. And I certainly have very little interest chasing
nutrients with test kits! I'm also seriously considering having a primarily
Hornwort thank, as that stuff seems immune to algae (and grows wonderfully).
My main concern is that I don't want algae covering/harming the plants.
Which reminds me of another question- beyond robbing the plant of light,
does algae on the surface or edges of plants harm the plants? In other
words, does algae leech nutrients and/or secrete chemicals that harm the
plant?

But it works on those.
There are trade offs, but the water changes + adding the nutrients back
is rather simple and very flexible with many light choices.
With a large fish load and an unwillingness to do water changes, it's
like cramming 10 people in a bathroom and not flushing the toilet for
weeks.........
If you want success, I will say you will need to reconsider your
approach.

I already do 25% water changes weekly (with a 3 gallon bucket- bleh!), so I
guess I would have to upgrade to a python-like system if I wanted to do 50%
changes. My comment concerning large fish load was whether I would need to
dose as much fertilizers as someone with a smaller fish load. Will I need
the extra K and P? Or even the N? Coming from an old-tank syndrome with
nitrates over 200ppm (down to about 20ppm now thanks to many weeks of water
changes and vacuuming!), I just don't want to end up overdosing my aquarium.

Say add lots of CO2, add K2SO4, and some KH2PO4 and some traces. You
might need a little KNO3, maybe 10mls of traces 2x aweek.
60% weekly water changes, should not take that long, maybe 20- minutes
to do the water change and refill.

How much CO2 is "lots"? I was thinking of making the 2L bottle DIY CO2
system.

With a high fish load, well...........I suggest something other than a
large pleco.

Yeah, I know he/she's a pain to clean up after, but he/she's easily my
favourite fish. Very beautiful!

3. Both are Red algae. Totally different genera, staghorn often comes
with high fish load tanks, (associated with NH4), BBA with low CO2. If
you do not add CO2, you need to stop doing water changes and
ramatically lower your fish load.
If you add CO2, you need to do many weekly water changes and add plenty
of CO2.
That's your choice. But you do not get both, there's trade offs
involved here.
I don't tell folks what they want, I just help with what they want to
do.......

What's interesting to me is that the Staghorn didn't appear until my
nitrates got below 30ppm, while the BBA was rampant at the higher levels of
nitrates.
Thanks again Tom. You told me exactly what I wanted, which was the
straight facts as you knew them to be. I'd really like the system to be as
low-maintenance/cost as it can be, within reason. To paraphrase you, I got
this aquarium to enjoy the flaura and fauna, not to play cleaner or chemist.
As an old-school (1980s) aquarist who never touched a test kit or live
plants, I inherited this big tank as a favor to someone who was moving.
It's certainly been an interesting challenge trying to convert it into a
balanced planted tank! Cheers,

Tony