sorry to be so late to respond I will also send a PM to you... That's a good question...
First I would ask if you have any light leaks in your res and the color of your res....
I ran into the same problem this last run because I had light leaks in my res... It also gave me a problem with gnat's...
Some nute's such as foxfarm's big bloom and a couple of other (organic) nute's should not be used in a res tanks....
To much oxygen can also cause a problem....
If your air stones have ( SLIME) on them, TOSS them...
I use small one's because I only use them for about a week...
Change your res every couple of days until you get a good fell after running the same nutes for a couple of runs and HOW your plants respond to them....
Im having what i believe is an algae problem i did a water change last tuesday and cleaned it all out the best i can but it seems to be still growing. I wrapped the resovoir with ducttape and two towels cleaned the best i could and been adding h2o2 every two days since this happened. Any advice? also i thought algae was green this is more of a white slime.