Lettuce and Germs... We've got mold
 

:(

I am very new to the world of hydroponics. I started with a 7 pod aero garden and enjoyed it so much I decided to try it on my own building own system.

I knew I was going to do some DWC and eventually ebb and flow and hopefully a NFT system for strawberries.

Anyway, at the moment I'm attempting to grow 12 Basil plants to give away as gifts. I've grown Basil before in the aero garden as well as in my own small dwc system with great success. Since I was growing so many at once I decided to move to a bigger resivoir. I went from using a 4 or 5 gallon tote to a 11 gallon tote.

I germinated the seeds in rockwool and when they started showing roots moved them to they dwc system.

Here is my current setup:
12 gallon tote with 12 holes cut out of lid, all black.
I'm growing in a 6ft x 6ft grow tent
I'm using a 45W Led light about 12 to 18 inches away from the plant.
The Basil is planted in Rock wool surrounded by Clay stones in 3 inch net pots. (I think 1 mistake I made was not putting the clay stones in first and having the rock wool sit on the bottom of the net pot)
I used filtered rain water, ph balanced between 5. 7 and 6. 2 and I'm using bloom and mico nutrients.
I have 2 air stones running 24/7
The light is on 12 hrs/day

So now to my problem.
I've started getting very dark mold around the tops of my rock wool and the clay stones.
I'm still in the learning phase so any help would be greatly appreciated.

If you see anything that I'm clearly doing wrong or could be wrong with my setup please let know.

https://imgur.com/qD2KOMP

https://imgur.com/EXmWZ4t