Replace Vanilla Potion Effect?

I'm trying to replace the Poison effect by doing
 

IForgeRegistryModifiable modRegistry = (IForgeRegistryModifiable) event.getRegistry();
ResourceLocation potionName = new ResourceLocation("minecraft", "poison");
AlteredPoison alteredPoison = new AlteredPoison(true, Potion.getPotionFromResourceLocation("minecraft:poison").getLiquidColor());
alteredPoison.setRegistryName(potionName);
alteredPoison.setPotionName("effect.poison");
alteredPoison.setIconIndex(6, 0);
modRegistry.register(alteredPoison);

The effect works when using the /effect command, but as soon as I use a Potion (splash, drinkable, ...) of Poison the effect seems to be applied but is not. Particles spawn but nothing happens.

Edit: Even tried using ForgeRegistries.POTIONS.register(alteredPoison) but with no luck.

Edited April 27, 20187 yr by Insane96MCP