If you find german blue rams being kept at the LFS odds are they've been acclimated to water parameters similar to what's coming out of your tap - and while they won't show their perfect coloration it's a lot less of a hassle to find them in that condition as you get used to high maintenance fish.
As has already been stated they're nitrate sensitive fish, I wouldn't go as far as to say anything over 20 ppm nitrate will kill them, but they become stressed and will definitely die in the 60-80 ppm range.
They prefer planted tanks, and will show a lot more interested behavior and far better coloration as well more of a readiness to breed if you can set up a heavily planted tank for them - which is expensive.
When you do want to get into breeding, you need to get your hands on an RO/DI unit.
To try and enduce spawning you do about a 70-80% water change with pure RO water that's about 2-4 degrees cooler then what's in the tank, it simulates the rain season in their natural habitat - which is their natural breeding trigger.
After they've laid you need to start to reintroduce water with a bit more mineral content, especially if they're in a planted tank - the best way to do it is to mix 50% tap water with 50% RO water and do 20% water changes every 4-5 days until you see wrigglers.
After you see wrigglers it's up to you on changing back to straight tap water or sticking to RO/DI water.
German Blue Ram are one of those rare SA fish that will survive and thrive in pure RO/DI water - but plants will not so you have to find a medium in between if you want them to be their happiest.
For good information on planted tanks visit www.aquaticplantcentral.com
Look up the conditions for caring for discus on various sites to get similar information to what German Blue Ram prefer, and if you're not an advanced hobbyist avoid any F0 (wild caught) fish you see.
If you want to just KEEP them, find some at the LFS, put them in a well established tank, keep the temperatures high and perform large water changes on a weekly basis.