[Ricardas]

I also have the same problems with java fern. But i am dosing potassium daily,increasing it by 5-6 ppm. Water changes are done with RO water adding potassium to 30 ppm. Iron is 0.5 ppm. But despite heavy potasium dosing ,leaves of polysperma show its deficiency...Other plants ,even so called difficult to grow , like eriocaulon setaceum,macranda,blyxa ,myriophylum tuberculatum are growing without problems. I noticed some improvement in java fern growth ,when i switched from KNO3 dosing for nitrates to seachem nitrogen. My idea is ...maybe my fern is unable to use nitrates due to high potassium level? I cant measure my potassium,but i would nor be surprised if it would be 60 or more ppm now.

 

[Ricardas]

i just got my water results from laboratory and here they are:
Mg 10
Ca 34
Po4 1,8
No3 24
Fe 0,56
According to fertillator ,recomended magnesium levels are 2 - 5 ppm. So it seems like i should remove Mg when reconstituting RO water. But on the other side Mg:ca ratio is 1:3 and it is ok. Gh is 6- 7 ant that is fine too. Dont know what else is wrong???

 

[Ricardas]

yes,these are my tank levels. Co2 should be fine ,because it is controlled by Ph computer and it is set to 6,5 - 6,4. my KH is 4-5, i know according to PH/kh co2 chart this should be too much ,but fishes are fine.
You are right about shading. polysperma is shaded,sometimes very seriously.But java fern is not a plant,that needs lots of light. But generally i agree that shading is one of the reasons that its leaves are turning black.