if I may jump back in. I agree with everyone also.
but if you want planted but so many recommend BB for juvies, if I may suggest, you can transplant your plants & set up various graveled glass cups or mugs or whatever receptacles & plant them that way. remove the rest of the gravel so it is BB. a nice compromise.
right now I have 6 stemless cosmo glasses all graveled & planted & so far so good. I also kept 2 potted swords in original plastic pots they come in but with their shoots I have planted the baby shoots as runners in my cosmo glasses (mind u I didn't cut the shoots just extended them sideways & planted like they were runner shoots).
the other thing I did to augment my maintenance is DIY my AC110 by extending the intake tube with pvc down to the bottom into a tee so I have 2 inlets. this takes care of sucking up all the heavier poop & with the waterflow action of my 2nd AC110 there is enough circulation to keep the tank clean.
my discus are "thriving" in that they are all very vibrant & still voracious eaters (feeding tetramin mixed with various kens flakes, frozen hikari brine & bloodworms, sf bay beefheart cubes & freeze dried worms from jehms).
mine probably won't grow to 7" (after 10mos.) tho they did double in size from juvies (again I bought mine from Discus Hans but kenny's is also a good choice).
I have chosen not to combine other fish since I have stabilized my tank & want to avoid anymore issues. but since you going in reverse, adding discus you still need to sufficiently QT them no matter the source. from reputable breeders you have a better chance of getting quality & not sickly fish but beware from LFS - almost always they carry with them ills.
so good luck! 180g is a nice home for discus presentation! at least 6 - 8 I say!!
edit
p.s. having 2 AC110's running the water flow is pretty strong, but counter to the fact they don't like strong flow mine are use to it & some actually swim up into the flow!! espec. when it's feeding time, when the food is dispersed I swear they act like piranhas!!