erovia

Hi guys I am new to pyro and I have been having a problem with my renders.
http://imgur.com/fFnhtSw [imgur.com]
Firstly its a little pixelated but I am sure I can solve this by upping the samples or running a better sim.

but the problem is at the bottom of the image there are lines running down the across the fire.

would love to know the reason.

Thanks

oh also if there is an easy way to add an alpha to the fire I would love to hear it.