Brown crypts, purple aponogeton

[Vahe Ganapetyan <vahe at hotbox_ru>]

Hi,

My plants show strange behavior - all cypts look well and healthy but,
as soon as I plant the "green" species (like C.affinis), all the new
leaves get the color of C.wendtii, or even darker brown. The leaves
also get some "pattern" like in C.aponogetonifolia - bte, the latter
gives normal green leaves. In the same tank I have an A.undulatus
which grows well but the leaves are browninsh or purple color.
Nomaphila grows well, but synnema doesn't grow high - it grows well
but stays near the ground.

Unfortunately, no test kits are available at my place so I cannot
analyse the water and have to rely on symptoms only. Can someone help
me in finding the causes?

THis is a 75gal tank with 180W lighting, CO2 injection
(~1.5-2 bubbles/sec, off at night), densely populated with plants and
some 80 not large fish. I add microelement mis every morning and make
about 20% water change in the night, clean the substrate every 10-14
days. I can see plants "bubble" with oxygen only after water changes,
before lights go off.

Any comments are much appreciated

Vahe