I had the same problem and just bought a new batch of WH instead of
playing around.

Bill Stock wrote:
I read something here a while ago about plants (Water Lettuce) and Algae
exchanging chemical attacks. Is there anything to this or is it just an old
wives tail? The reason I ask is that my Water Hyacinth is dying off, it's
all turning brown and mushy around the edges. The leaves that are healthy
seem to be a good colour, but the outside leaves and pontoons are all split
and brown. I've been adding trace elements and Potash for a few weeks and I
even added some Nitrates (5 PPM) last week. The roots are constantly covered
in Hair Algae, so I'm wondering if it is having some sort of chemical effect
on the WH. So far the Water Lettuce does not have any Algae on the roots,
but I suspect that's more a matter of duration. It's only been in the pond
for a few days. Salt s/b zero, but I'm tempted to check at this point.

Any WH rejuvenation advice would be appreciated.

TIA