rwdyredhead, Green75 told some one on an other thread to rinse the roots well with water and H2O2 in it. I have used H2O2 in the reservoir to kill it, but it takes a while, rinsing the root ball may speed up cleaning out the slime. The store variety of H2O2 is only a 3% solution, so you could use it full strength to rinse the roots. The preventatives, good oxygenation of the water, lower temperature, and sealing off light intrusions, are far easier than killing it off. I replace all of the lines (air and irrigation), air stones, and water pump new each time, if you can't boil it, toss it. The reservoir and net pots get cleaned with dish soap, an over night soaking in a strong (2 cups per gallon of water) bleach solution, then rinsed first with water and then a solution of Florashield (2 Tbls per gallon) in water. I have used the Hydroguard, but I have had better results with the Florashield. Do not use the Florashield if You are using 'live' microbial supplements. An agent from GH told me, in an e-mail, that it could be used directly in the reservoir, but no more than at 2-3 ml per gallon.