[reefclown]

The concept is to circulate only whilst getting the reactor going, seems little point in adding oxygenated water when you are trying to create an anaerobic environment. so long as there is nitrate present you wont get hydrogen sulphide. This way when you see some gas forming at the top of the reactor it's probably time to start dripping (after the usual tests that is).

I've done things in reverse, in that I've converted my calc reactor into a sulphur reactor to see how it will operate.

When running as a calc reactor I used to drip from both the standard exit port and the central port to vent off any excess c02.