What yeast are you using? I just did four different beers using either NovaLager from Lallemand or Mythical Hammer from White Labs. Both are hybrid lager yeasts that ferment clean at mid-60s temperatures for lagers. Mythical Hammer was a joint venture between White Labs and Clawhammer to develop a pressurized fermentation lager yeast that works well at 63F-65F. Coincidentally, I used that one to brew a Helles.
The NovaLager is a dry yeast for warm lager fermentation, and though not specifically engineered for pressurized fermentations, it performs quite well.
I started all fermentations at 63F and capped at 6 psi CO2 pressure. As soon as I saw a pressure rise, I attached a spunding valve set to 1BAR/14.7 psig and let it rip. After 4~5 days the SG was within 5 points of estimated FG, so I raised the temperature to 73F for diacetyl rest. The finished beers are all very clear, well balanced, clean and no diacetyl, following cold crashing to 38F.
To say the least, I am very pleased with the results, both with the yeast and the pressurized fermentation process, which resulted in finished lagers in a little over a week grain-to-kegging rather than my ‘normal’ month or more.
Wednesday I’m planning a brew day making a classic West Coast IPA (Simcoe, Cascade, Citra), but brewed as a ‘Cold’ IPA (half Pilsner malt, half 2-row pale ale; brewed at 63F@1 BAR with Mythical Hammer harvested from the previous brew sessions).
I’m lovin’ these new yeast strains under pressure. Clean and fast, and I think they present a better finished product.