So I recently just switched from hand-watered coco to DWC. I'm using Coleman coolers with holes drilled out in the lids. Temps are not really an issue. I had the smallest light leak around where my air hoses come in but that has since been plugged. I'm using only FloraNova and Roots Excelurator with Toronto tap water (100ppm starting). Some plants are more affected than others. I've never grown in DWC before (or any kind of hydro) so I'm not sure what to expect but my gut tells me something isn't right. The roots feel a bit mushy and not like bean sprouts (except the really white, fresh roots). The browner, more slimier roots (only faintly slimy) seem to pull away easy but the plants look healthy on top. I've started applying h202 (27%) at about 1.5ml per gallon every few days but it doesn't seem to make any difference. The res itself has a very, very faint pond smell. I'm not being overrun by "slime" but at the same time I don't think things are right. This isn't a RDWC. Each cooler is independent and I clear the res with a submersible pump followed by a shop vaccing to get what is left. Changing res every 7 days. Res temp fluctuates between 60-70f. Aeration exceeds 1 watt per gallon with airstones. PH is also stable. I started out in coco and transferred the coco root ball into hydrocorn (thoroughly washed first) so there are actual fleks of coco in there causing some discoloration but there is also a slimy/mushy feeling to the browner roots and they pull away very easy. I know Floranova is supposted to stain roots a tan colour. I am thinking this could be brown algae (cyanobacteria). I bought some physan 20 off ebay just in case as this seems to be the only thing that consistently wors for that and am going to get to work brewing a benny tea today to fight off any bad bacteria that might be in there. See pics below. I've slowly been phasing in this DWC system over a few weeks as my hand-watered coco crops have finished up. All systems appear to be effected. Some plants all have much poorer root mass despite receiving identical treatment. I'm growing from seed so different genetics but same strain. Pics below. Each pic is from a different cooler. The middle pic is from a batch that is a few weeks ahead of the 1st and 3rd pics. Blargh. Any help appreciated. And I thought DWC was going to be easy as long as I kept my temps low. Guess I have some fine tuning to do. I'd add that no air stones or airlines have a slimy feeling to them. The walls of the res also do not have a slime feeling. The closest thing to that is a bit of discolouration at the water line but I think that is just nute residue from the floranova as the water level has dropped.