"Michi Henning" wrote in message
...

BTW -- you should try to get those nitrate levels down. 100ppm is
definitely on the very high side where it will be toxic for at least some
fish species. Adding lots more plants will help in reducing nitrate
levels.

At 100 ppm NO3 there is some evidence that plants themselves shut down at
normal (0.05 - 0.1 ppm) Fe and trace levels.

Graham .