I have a 3 vessel HERMS system. My HLT is a 15 gallon keg with a 50' stainless coil in it and the MASH TUN is a 15 gallon keg w/ a SS false bottom. I am running two pumps. My question or issue is with the MASH Tun. I find that my grain in the mash tun gets sucked to the bottom of my false bottom...