Thanks. I used these LED's with a colour temp of 6500k.
https://australia.rs-online.com/web/...e-led/6729063/
I might try the 9000K ones or just use the green flats.
I read in the qhy forums that the flats need to be used with the Bias. so might try that as well.
I've been trying out ccdstack and it seems to produce better results than DSS, but with software such as this, do I need to create a master flat or calibrate the flats with darks or bias? I believe I won't need bias frames if I use darks.