I baught Methlyene Blue to treat my angle eggs. I used 6 drops to 10 litres of water like the bottle said. It gives no more instructions so I do a water change after or just leave the water and put more drops in the next day.
Don't be shocked to see fungus on the eggs either some may not have been fertilized and will hav fungus. the M.blue will help the rest from rotten away. Good luck.
Don't add more you should be fine until eggs hatch.