a bag of coco loco says its 50 to 80% coco fibers ...

You have a Coco/perlite mix , if your original coco mix contains between 50 to 80% of coco fibers it should contain 50 to 20% of coco coir , to me their is a difference between fibers and coirs but both are coco ( I am using the fibers from local caribbean coconuts to improve my soil while I am using the coir to stricly grow cannabis ) so when you add 0.6 kg ( 1.5 pounds ) of perlite then you only add more "soiless" medium. So no soil but mostly coco in your case. In coco to correctly feed you will have to bring Calcium and magnesium ( cal/mag) with every watering because coco medium is cal/mag free . Your feeding schedule will also be different from a soil schedule , maybe similar or close to an hydro schedule because the Ec /ppm level are higher in coco and hydro than in soil. Last thing and the most important is the Ph of the medium , it should be 5.8PH ( the sweet spot ) even if you can start at 5.5 and slowly increase to 5.8 then 6.0 or 6.2 but it's better to stick to the 5.8 ph sweet spot if you are a begennier to keep it simple , and you will have to double check the ph , as you need to check your watering solution PH BUT ALSO the water runoff PH ( and ppm ) to see if there is a difference between the input and the outpout and do a PH fluctuation : if the output PH is different then correct the input ( for exemple if your output is 5.7 then watter with a 5.9 ph input to get back to 5.8 )