Thats where i got the 8.5% from was clorox. I had a couple of really nasty R.V.'s one day that were almost totally black and green. I didn't have the time to get 12.5% so I went to home depot and saw the two different options from clorox. the regular was 6% as per the bottle and the outdoors had...
12.5% sodium hypochlorite (bleach). You should be able to get it from local chemical suppliers or a pool store. First try the outdoor results its 8.5%SH and use a pumpup sprayer to achieve all 8.5% on the surface. If you use the 12.5% and Downstream it your at best looking at 8.5% on the surface...