Hi all, Wanna first say how helpful RIU has been - thank you all. Topping up my DWC res last week, I had mixed extra nutes, so I put an extra 2 gallons aside in a 5gal bucket. I had a pair of air stones going in it. Today, I went to pour this water into the res, and I noticed a gunky/slimy buildup on the airstones. No smell. Took a pic of the stuff floating in water too, it looked a little like phlegm. I'm using hydroguard; does anyone have any insight into or experience with this kind of build up on the air stones? Was there more room for whatever is in hydroguard to grow, since there werent roots in this bucket?