Re: C, H and O %

[Thomas Barr <tcbiii at earthlink_net>]

From Epstein 1972, 1994:

Concentration in dry matter %
_____________________________

H-6%
C-45%
O-45%

in umol/gram
____________
H-60,000
C-40,000
O-30,000

About all you'll note is that most of the plant mass is from Carbon.
So adding CO2 can really help. Oxygen, Carbon and Hydrogen are not usually
consider mineral elements, due to being obtained from mainly from water and
or carbon dioxide(not lacking in terrestrial  plants for which many studies
are for, such as this one).

You may want to note that this information is _not specific_ for aquatic
plants nor species.

FW algae has about 14:1 N:P ratio
FW plants about 10:1 N:P ratio
The Redfield ratio is 16:1 N:P and is for Saltwater algae.

The above is comprehensive for the FW algae, the aquatic plant portion is
for 25 common submersed aquatics.

Regards, 
Tom Barr