Agree. With 0 measurable phosphate and around 5ppm NO3 I find that BBA will
grow in my tank. The NO3 is added (in the form of KNO3) to keep the level
at 5ppm as without that addition it will drop to zero and other algae seem
to blossom at the expense of the desired plants.

Focus should always be on the plants, not the algae.
Take care of the plants and you will not have algae.

Interesting hypothesis. I've been running my tank at 20ppm CO2 which must
not be enough. I've just added enough Baking soda to increase the level to
30ppm CO2 - the pH controller is (at the moment) sending out millions of
bubbles of CO2 to lower the pH :-)

Try adding a bit more CO2, measure your night time pH right befiore
you turn off the CO2 and also make sure the probe is good and that the
KH is actually 7 etc. Good in tank mixing also helps to get enough CO2
to the plants also.

Adjusted PMDD formula fed daily to balance nutrients
Heavily planted at the moment with elodea (throw away weed - pruning around
6 inches from each stem twice a week) plus other more important plants.

Regards
Graham.

I think your KNO3 dosing is too low.
The Trace mix I add is about 10-15mls 3x a week for a tank this size.
You can divide this into daily volumes, but that is much better than
any test kit reading you can provide. Iron test kits do not tell a
planted hobbyist much nor what they need to know.

You can try addin gthe PO4 via a Fleet enema(a few$ at a local drug
store, sodium phosphate mainly, get unscented etc) and add about 4-5
drops and then watch your plants. Add it in the morning and then note
your tank's condition later before the lights go out.

Add about every 2-3 days.

Paul and Kevin's paper is widely read, but assume algae can be limited
by PO4 and is only 2 cases studies, not the best controls in the
world, nor proves anything and is with low light and NO FL's bulbs.
CO2 is set about 1/2 full CO2 saturation for aquatic plants(about
30ppm for many species) This PO$ limitation is far from true. Well
heck, you can see that for yourself in your tank. And you are not the
only one, many have done this and I've watched them and tested their
tanks in the past.

Here's my tanks that I add lots of PO4 too:
http://www.picturetrail.com/gallery/...32&uid=1473668

Also the AGA folks generally add PO4 to all their tanks:
http://www.aquatic-gardeners.org/

Under "aqascaping contest"

BTW come see Amano this Nov

Now you can decide what is correct or not yourself. Some of the
approaches such as dosing macro's and taking better care of the
plant's needs is very helpful and led to better horticulture of
aquatic plants, so it's still a very good read, but careful assuming
too much.

If you are still not convinced, you can come down and see a 6 mile
river full of plants that comes right out of an old PO4 mining
operation.

Regards,
Tom Barr