Not sure if this will be seen as the last time anything has been put on here was awhile ago, but this may help someone. I am doing a RDWC grow. I have grown many different ways and tried hydro several times with the same problem... root rot. I am now trying it again and am determined to make it work. I have been using beneficial bacteria, but hasn't worked for me. I have switched to 3% h202 at 3ml/L. It didn't seam to help so I kept increasing the amount. I would rather kill the plants than have root rot get them again. I have plants in bloom and ready to cut in a week or so and plants in veg that will take their place. I am now up to 8ml/L of 3% h2o2 and adding 25% each day. So for example... 100L res gets 800ml of 3% h2o2 and every 24 hours 200 ml of 3% h2o2. If I add 20L to the res(water or nutes) I add 160ml of 3% h2o2 for the 20L(20x8..160) and 160ml of 3% h2o2 to the main res. I work it out this way....res down 20L... so there's 80L nutes in it that has h2o2 already added... to make up h2o2 ... 80x8 is 640ml h2o2 and 25% of 640 is is 160. So I would add 320 ml h2o2. 160 ml for the new 20L of nutes and 160 ml for the make up of the old nutes. I think I have been able to get through the flowering period because of this although it has not cured the root root. The ones in the veg started to get root rot before I increased the amount of h2o2, but it hasn't gotten any worse and for the most part the roots look great. Hope this helps someone.