Hi guys, I'm a newbie to fountain pen and recently got my first pen, a Lamy Safari. I was using one of the Lamy ink cartridges but for some reason, the ink 'disappeared' from the paper after a few days. I'm a student and I'm trying to find a blue ink that's slightly brighter, a similar colour to Zebra's Sarasa Cobalt Blue (not an FP). I've sort of stumbled upon Pilot Iroshizuku and I quite like the colours Tsuya-Kuya and Ama-Iro. Can someone help me with some of the pros and cons of these two inks? Are they good and is it worth the price? Thanks so much in advance!