Fuzzy Guppy

[RandomTask]

I got two new guppies two days ago. yesterday I noticed that the female had an area of what looks like white fuzz on her back. Then this morning she has a white spot on her right fin. Her fan fin also has a plit in it. Is this white spot? My lfs warrants the fish I buy for 48 hours should I just take her back. I'm new to fish keeping, and I've had this tank for about one month.

it is a 10 gallon tank with 3 platies in it as well.
Ammonia - 0
Nitire - 0
Nitrate - 5
PH - 8.2 (the PH has always been on the high side)

 

[WILDER]

Columnaris with a second infection with the finrot, does the fluffy bit on the back form a saddle look to it.
http/www.flippersandfins.net/flexibacter.htm

 

[RandomTask]

That looks like it, thank you for the help.