Wow, I cannot believe this thread is still going. I was on here about 2 years ago (around pages 90-100) trying to get help about the slime issues I encountered after first purchasing my UnderCurrent system. I stumbled upon this forum and read about Heisenbergs tea. His method of his tea brewing was an absolute success, and worked 100% for me. But realized that it was a pain in the ass to go out and buy these items from the grow store every single batch, especially seeing as to how I have 16 buckets that are 13 gallons each (over 200 gallons of water) . This is taken from the 2nd paragraph of his first post:
Several root conditions will cause a slimy build up; doesn't mean you have the brown slime. Common root disease is almost always caused by improper res conditions, and they improve greatly when those conditions are corrected. This isn't true of the slime. When to suspect brown slime algae is when you are doing everything right and still can't get rid of it. People who get this try the normal stuff... More bubbles in the water, cool res temps, and h202 treatments. The slime may appear to be gone at first, but comes back strong in as little as 12-36 hours. It starts out subtle like a clear coating of mucus on the roots with no odor. Plants often still appear healthy for a while, but all root production stops. In a very short time it will cover the entire root base and become thicker and sometimes turns yellow. Eventually it strangles the roots which causes pythium to set in, and at that point turns brown and finally has an odor.
What he's saying is that you pretty much have to live with it, as long as you maintain it by brewing and using the tea though, it will keep the slime away from the res. I do not grow in individual DWC buckets, I use an UnderCurrent system, and I was getting really annoyed by the tea brewing. I maintain incredible res/room conditions for any grow. The room never goes above 83 degrees, humidity is always 40% or below, and we have chillers to make sure that our water is always around 65-67 degrees. I went to a friends house recently who had also just purchased the UC system. His indoor environment was nowhere near as maintained as mine. His room was above 90 degrees, his water temperature was about 75, and humidity was over 50%. I asked him if he had any issues with slime, he said "never heard of it, dont know what you're talking about". I was baffled, and didn't believe him. So one by one I looked through every single 13 gallon bucket and saw he was absolutely right. It didn't make sense to me. So I started asking myself "What is he doing that is different than what I was doing?". I finally realized what it was.
I had already placed thick black trash bags around all my buckets (as did he), but the one main thing I DIDN'T do, was cover up the white tubing connecting all the buckets together. He had also placed styrofoam plates on top of the hydroton and tape around the top part of the net pots (where light was still apparently getting in). So I go home and do this. Low and behold, the slime has never came back since (2 years now).
As far as people who are growing in individual DWC buckets, I can only tell you that you are most likely letting light get in, and that if you are using any buckets or netpots other than black ones, you should definently replace them. As far as UC users go, if slime is a constant problem, and you are brewing tea for every single batch, make sure that the piping that is connecting your buckets are either black, or covered with some sort of black tarp. I even covered the manifolds of my UC. Not saying that the tea doesn't work, but I never have to go out and drive to the grow store and spend more money on the ingredients of this tea. Hope this helps!