Different strings for different tuning?

For D standard you should be fine with whatever is on your bass. When you are just learning, what's wrong with regular tuning?

 

Just a step down to d you should be fine unless the strings are really light gauge. If things are too loose for your taste try a medium or medium heavy gauge

 

You're going to learn from one band?

 

I'll have to double-check this when I get a chance, but are you absolutely sure the bassists for Ghost downtune? I learned a couple of Ghost tracks as combined singing and playing practice (Square Hammer for sure, don't remember the other title off the top of my head) and I didn't have to alter my tuning for either.

 

.045, .065, .085, .105 are good strings for me on standard EADG tuning. You can try DGCF tuning on those gauges and see if there is enough tension for your playing style. If not, increase each string gauge by .005 and you should be good to go. Not sure if the nut on your bass will handle it though.

Also, I highly suggest taking the strings off your bass and getting a new set installed. You have no idea how old the original strings are and how much you can improve the tone of your bass.

 

Most string gauges are sold to be at a certain tension, more or less, when tuned to EADG. If you detune any or all of them and want to keep the same exact tension or tone, then those strings need to be a heavier gauge or you need to learn to like the floppier feel and tone.

It's simple mathematics.



Now, if you want to be able to change tunings often you need to compromise and select a string that has the desired tension at a note halfway in-between the two extremes of where you are wanting that string to go.