"D&M" wrote in message ...

Your 15-0-0 provides potassium and, I suppose, iron and trace elements.
I use "Plant-Gro"
-0.15% nitogen
-0.26% iron
-0.05% manganese
-0.003% zinc
-0.0005% boron
-0.0005% copper
-0.0007% molybdate

Oh! Then I was mixing up the numbers for nitrate and potassium. (This means that
Jobe's spikes for ferns and palms are actually 16% nitrate, 2% phosphate, and 6%
potassium)

The nitrogen in Plant-Gro is only used as a chelating agent for the traces. So it's
"0.15"-0-0 which is not the same as 15-0-0. It is essentially 0-0-0.

treatment is 5ml/10g... no instruction on how often to add, so I add every
couple weeks after I do a 25% water change.

The recommended dosage amounts to adding 0.3ppm (=0.3mg/liter) of iron. That may be a
bit much. 0.1ppm is usually recommended here as a target. (Much more than this can
lead to algae problems, especially if there is also an excess nitrate.)

Assuming zero iron intake you'd need to add 1/12 of that doze after each water change
to maintain 0.1ppm but that's an unrealistic lower bound. If you add 0.1ppm after
each water change (1/3 the recommended dose) then, (still assuming zero intake,) your
iron concentration will stabilize at 0.4ppm which is not catastrophic. So you could
safely start with that and monitor your plants for signs of iron deficiency.

Check this useful article on Chuck Gadd's page for a table of nutrient deficiency
symptoms:

http://www.csd.net/~cgadd/aqua/art_plant_nutrient.htm

What is your tank size?

90g

What is the lighting wattage?

42" 40w Power-Glo Flourescent.

What are the other plants?

No idea what the names of the other plants are, here's a pictu

http://www.execulink.com/~sharp01/plants.jpg

This might be elodea densa or hydrilla verticillata on the left, I am unsure. The
other one : hygrophila? ludwigia? Both seem to be fast growing stem plants that
would normally need a steady source of macronutrients (K, NO3, PO4) to do well but
you lighting is very low. So maybe your fish load (+Plant-Gro) is sufficient to
provide all they need. You could also burry half a spike or root tab, deep in the
substrate, bellow each bunch of stem plants, every two months or so.

I'm still using designer gravel, haven't grown up enough to move to sand (to
lazy to change over is more like it)

So am I. I only fertilize the water column and use a few spikes. However I have high
lighting and CO2 injection. One drawback of a poor substrate in these conditions is
that stem plants produce lots of roots at the nodes to get nutrients from the water
column and this is somewhat unaesthetic.

What is the fish load?

4 med. bala's, 12 tiger barbs (reg&greeny's), 1 pim. cat, 8 loaches (3
clowns, 2 yoyo's, 2 zebra, 1 "tiger"), 7 assorted cory's (pandas, peppered,
albino), 7 otos, 1 clown pleco, 4 serpae tetras

Under your lighting conditions this is probably sufficient to provide enough nitrate
for your plants. It is certainly sufficient to provide enough phosphate. If you see
pinholes appearing in the older leaves of your plants then you will have to
supplement potassium, which is the most likely macronutrient to become depleted in a
fish tank, even under low light. The target for this is 20ppm and it does not promote
algae growth.

I don't suppose you are injecting CO2?

Not yet, looking into a good system as I got fairly high pH, kill two birds
with one stone, so to say.

You might want to look into improving your lighting, also, if you want to seriously
get into plants. It is frustrating to put care into this only to see them slowly
whither away and disappear into fish and snail.

What I'd really like to know is how to make the "Big" leaves like the parent
amazon plants have. Do I have to prune some of the leaves off to encourage
larger ones to grow?

I'll let people who are more knowledgeable about amazons answer this.