Are EPS precipitated by 95% ethanol at 4'C visible to the naked eye. I am precipitating with ethanol in 15/50ml tubes for 24 hours at 4'C and then transfer the solution to 2ml eppendorf tubes and centrifuge at 16800g for 1 hour at 4 degree Celcius. However, I didn't observe the precipitates in the 2ml tube. Is it normal or not? I am transferring to 2ml tubes because the centrifuge in the laboratory I am working can only reach 16800g with these tubes. Can I use 6000g with 15ml tubes?