The level of zero point five is pretty far away from what I'd consider a nightmare. Phosphorus is one of the major nutrients that plants need for growth, thus you need at least some in the water. I maintain a level of four times that much in my aquarium -- intentionally.
You may want to take a step back and reevaluate the chemical filtration you're using, there is very little need (none, in my opinion) to use phosphate absorbing resins or water softening ion exchange resins. You could put the money that you're spending on that sort of stuff toward your "Eheim fund" or whatever filter you'd prefer to have over your Fluval.
I don't know what your GH was before the softener pillows, but ~5-6 degrees isn't bad at all, plants need the minerals that make up a GH reading too.
What chart are you using that .5 would be considered "off" of it? My API test kit for PO4 starts at .5 after zero.
Actually I just saw where you said the Aquarium was at 5ppm, is that right? That second post wasn't there when I hit reply. If you don't have any fish in there, I'd recommend a 100% water change, if you have fish then a 50% water change. It'll at least "reset" your tank, in a sense.
What is mopenny? Mopani wood? The tannins released won't soften the water, they'll just lower the pH, your GH (General Hardness) won't be effected .