Randomness

Ok, well to start off, I'm 17 and we moved to a house about 8-9 months ago. My mom is not a fluent english speaker so I'm here in her stead, but she's been busy working and me with the school year so we haven't had time to do anything with our spa. The other day when we went to see if it even functioned we filled it about 3/4 full with water and turned on the pumps and, to our suprise, black semi-transparent things came out from the jets. We assumed it was mold of some sort or something but we didn't know for sure what it was or what to do about it. So now I looked around on the internet and I ended up here. I've read through alot of posts and I'm still not sure what to do next. Please, any help would be greatly appreciated. FYI: The spa is outside and I'm not sure if the previous owner used or even properly maintained the spa. Thank you again for any help. -Glen