I would try lowering your water, I had mine too high at one point and got poor growth. I lowered it another 1/2 inch. Now the HC is taking off like mad. I mist the SMS / HC 3-5 times a week with a solution of excel and highly diluted miracle grow. I think I used 1/2tbsp for a large garden size spray bottle, and 30ml of excel. My emeresed setup is a 90g with 2x150mh and 2x55 ah supplys for 9hrs/day. I have massive root balls 2"-3" deep.
Another thing I did, BEFORE lowering my water (I had nasty green/brown sludge in places..) I filled the tank 1/2 way.. tossed in a power head and dumped about 150ml of h202 into the tank.. and all the nasty stuff bubbled away.. let it soak for 4 hours, vaced it all out.. filled and drained 1/2 way 3 times. I didnt notice any effect on the HC.
Epic, I too found a leaf of duckweed in my emeresed tank.. However since I lowered the water farther.. the four leaves.. have turned WHITE.. I then removed them and havent seen another one. On another note my 20l that had a duckweed problem.. it started to die off for some reason
Lets just hope my other plants dont lol.
The world is a tragedy to those who feel, but a comedy to those who think.
Horace Walpole (1717 - 1797)
Nearly all men can stand adversity, but if you want to test a man's character, give him power.
Abraham Lincoln (1809 - 1865)