Seedling trouble / Microorganisms/ Algea coating roots

What up roll it up crew! I have in my possession 3 seedlings. out of a batch of 7 4 have died from lack of water up take. They are currently sitting in 2 inch rock wool cubes and have been fed 5.5 ph water for the past week and a half.

Here is my problem. The roots have not penetrated the bottom of the rock wool cube and its been almost 2 weeks. As well i fed the seedlings water/molasses/sea kelp and a microorganism by earth juice which contains a shit load of microorganisms. What has happened is the microorganism coated the roots with a algae like film "brown coating" and i think its hindering the growth of the roots. this is what i Saw on the ones that didnt make it, all the same.

So my question to you all is how would you either A kill the algae "brown coating" on the roots with out hurting the plant. B what will allow the roots grow good enough to establish a base into the soil.

If i can get the roots ot go through the bottom of the cubes ill be fine but i just need them to grow!.

PS i see roots at the bottom of a rock wool in add least 5 days max and all the ones that died never made it

Thanks for the help all

I dont know much bud but i do no brown crap on roots is not good the roots are the life off yer plant m8 look after them and plant will look after u

I hate germing seeds in Rockwoul, check out rapid rooters

Do you have to use rockwool? I would recommend potting soil/soilless mix with minimal amendments, such as Sunshine Advanced Mix #4. Starting the seed in a container at least 4" deep. Media should be somewhat moist at all times but not constantly saturated or sitting in stagnant water.

What microbial product did you use exactly; and how much molasses? Avoid using the molasses excessively.

Under the right conditions, with good moisture, oxygen, and beneficial organisms in the media, the presence of high numbers of good organisms should keep pathogens at bay.

Nothing wrong with rockwool. People use it all the time..and I used it for all seed starts and clones for 4 years straight. No problems. It's the other crap you put on it. I suspect the brown is nothing more then molasses residue and not an "infection". Just use water till you see a tiny bit of tip yellowing. Then start adding nutes at 1/4 strength. Go PH 6 or thereabouts.
JD

Rockwool is actually very popular as a rooting vessel. But just like others out there used for the same purpose, it also has disadvantages.
For a good number of growers, the pros outweigh the cons though so they use rockwool.