Polly's Pets has pods I believe if you want to seed it. If I remember correctly the ReefPods have the Tisbe sp. in them. Those are more sustainable than the tangerine/tigger pods in a reef tank.
And YES! they will do well on your diatoms. That's why you usually see a big pod bloom right after the tank is done cycling because they reproduce very well on diatoms - more so than on any other stuff they find later.
Also makes it kind of deceiving because people think 'WOW I got tons of pods' and assume it always will be like that.