60 liter tank? That's 15 US Gallons. And you had a tire track eel, an angel fish, giant danios, two silver sharks, 6 phantoms in the tank??? You also mention 10 swordtails??? All at the same time? I'd suggest (very strongly) your problem is overstocking.
Not all overstocking problems show up in water parameters. Often times it can be territoriality, fish just bumping into each other, causing stress, resulting in fish death.
What fish do you have in the tank right now? If it's as heavily overstocked as it sounds, you have no other option but to rehome most of your fish or buy a larger tank. Sorry for the stark news. HTH~