Yeah the vals is thr only plant growing on the internal filter side. I dont like the stringy look of the java moss and will take it as a last resort. Microsword is also a bit too long but will take it over the java moss. Anything similar to Marsilea Minuta but easier to grow?Ah, try to find Microsword; it's easier than dwarf hairgrass, needs lots of root tabs but will work. Takes a little while to grow but it will get there eventually with some care and nurturing ^_^
And no, Java Moss won't hurt the filter, it may be a little difficult to clean but you just need to squish/squeeze gently the sponge every now and then. Don't put it on the internal filter though, let the Vals grow bigger and they'll cover it eventually.