Bro Martian is right. Increase WC will definitely helps, but battling with algae issue need patient. Sea urchin are excellent help. Live rock are possible source of nutrient leak. How big is your tank anyway?
If you have ich issue, is good to stop adding fishes. Fish die, decay, nutrient spike, more algae. Run UV light if necessary, will kill ich.
As for your snail, did you acclimatize them properly?