I called the Clayton company (website: http://www.claytonchem.com) and the guy said that the time should be 9.5 minutes for HP5 pushed to 1600 based on his chart. This is using 1+9 dilution ratio. So I did the math to see if the 15% rule applied and it pretty much did... using the time for 68 degrees (7 min) x 30% = 9.3, which is fairly close. So there you go. Hope this helps.(posted 7977 days ago)