Need help. Discus eggs turning white

[Danny77]

Hi to all. I need help guys. I have a pair of discus both 5 inch (13-14cm) she is a blood pigeon blue and him a red velvet. I keep them both in a tank 120 liters and yesterday was the 5' times she laid eggs on the cone and him passing with his tube right after her. The problem is after the 24-36 hours all eggs become white and don't know why. Water temperature is around 29-30 degrees Celsius and the PH 6.1,the other parameters don't remember but used tetra 6 in 1 and all were on OK line. My filter is juwel eccoflow with sponges, white stones (don't know engl name) but not carbone active. When she laid eggs I always stopped the filter pomp to help him fertilised the eggs. Don't know what the problem is. Pair too young? Male not mature enough? I read some use methiline blue on eggs, i tried that yestarda
Y but eggs turning white even faster. Help me pls2148421484