ok ill try mate, will my plants die now?
No. Unless you kill them.
Those look like pretty big rockwool cubes. Gently dig out the top layer with a knife (it's just spun fiberglass, you should be able to remove like a quarter to an eighth of an inch without touching root) just be careful and use your common sense. This will also create a nice lip with that plastic wrap that will support a single layer of pellets.
Once covered, your reduced watering schedule should help. Yeah, the massive algal growth is an indication that there was too much moisture and not enough absorption. Remember that the roots need oxygen just as much as they need moisture. Your plants should spring up, but if they continue to look yellow, increase your Nitrogen if you can.
Edit:
Oh, wait a minute, boss. It just dawned on my why your plants are suffering and why you have that thick layer of algae.
Here's what you gotta do if you want to save those babies. Dig out as much of those pellets as you have to in order to remove that white plastic wrap entirely. Then re-bury it. I just noticed you had so much of that plastic covered rockwool buried in the pellets. It's meant for the roots to growth through that rockwool block and into your pellets if your gonna bury it that deeply. That plastic wrap is also responsible for trapping too much moisture in the dense rockwool block. The whole thing has to breathe with each drain. That should fix things. And you should be able to do it without shocking them if you're gentle.
For future reference, when planting rockwool cubes in clay pellets, bury it deeply enough so that the surface of the rockwool cube is just about a half inch under the intended surface of pellets... just enough to bury the surface of the cube in a single layer of pellets. No plastic wrap.