I'd do what pastafarian suggests. More Perlite. I use Promix and still find that i need to make it a 50/50 blend with Perlite even though it is already in the mix.i had that issue in FFOF. the soil compacts, exp after flushing a bunch of water thru it. next time add perlite, it helps prevent the compacting. to fix your issue, set a fan up to blow on you soil, it might take a day or so, you still might want to add a few more holes in the cotainer bottom to help with draining in the future.