Perhaps you can give us a bit of information, and then we can help you?
Firstly - are you doing the fishless cycle - in other words adding ammonia into yor tank to build up the bacteria in your filter? If that all sounds double Dutch to you, have a read of the information on Fishless Cycling here -http://tropicalfishfanatics.forumsmotion.com/cycling-and-water-chemistry-f70/fishless-cycle-t227.htm
Feel free to ask as many questions as you need to about it - we have all been through it and know what it's like!
You mention you have hardwater - have you done any tests to give you an idea just how hard? If so let us know. It can be a pain trying to constantly alter your aquariums water parameters, and as mentioned it is much easier to find fish that will be happy in whatever water you have. If you could let us know your tapwater ph (leave to stand for 24hrs before testing it) then we can advise you on what fish will be happy with that.
Dont worry if this all sounds a bit daunting - it's not really, and there are plenty of people here who can help you with it
TROPICAL TANK-Elite Tank - 207litres
6 Harlequin Rasboras, 5 Emerald Eye Rasboras, 10 Cherry Barbs, 2 Bristlenose Plecs, 2 Panda Corys. 4 Dwarf Chain Loaches.
ViaAqua Tank AR620 97litres
1 red male betta, 1 BN