it is bypassing the media. there was many guys couple years ago on Polish forums talking about having the same issue . How dirty are your hoses? my outlet hose is as dirty as the inlet hose which mean the water coming out the filter in not clean when on my eheim classic the out hose is much...
This is common problem with them. I have the 901 and 1501 and the both have the issue. I'm done with JBL products the filters are crap, filter hose cleaning brush falls apart after using couple times and the co2 indicator loosing liquid.
I'm having similar problems with my Rotala and getting fed up with it. The only time my rotala looked good was when I went on 2,5 weeks holiday and left it without any ferts but at the same time other plants suffered.
I'm using nature one in my low tech tank and plants are growing good. I have used combination of day and nature when I had high tech tank and plants were growing and turning red. You should worry more about co2 then the lighting.
Anyone have any experience with this led light unit?