Delbeek and Sprung Volume 3 suggests that the volume of sulphur beads be 1% of the water volume. This book was absolutely the best source for information as I was researching and setting up my reactor.
I have 4 gallons of beads for a 500 gallon system, so a little under 1%. To start off, the flow rate needs to be extremely slow (this is very tricky unless you have a nice system like reeferaddict with fine controls - if Korallin had a much larger unit I would have seriously considered that). The drip rate for starting is in the range of 1 drop per second per half gallon of sulphur
- that's tough to regulate in a DIY design!
Once cycled (mine took about a week), flow can be increased to around 1 gallon per hour per gallon of sulphur. The flow range seems to be quite forgiving, unless you can't get the flow fast enough due to constricted tubing ... hence my Annacis Island situation. As the nitrates dropped, I found I needed to increase the flow rate into the 8-10 gallon per hour range. I upgraded to a Mag 7, and still needed to redesign the plumbing with 3/4 inch PVC to get the necessary flow.
The smell can last 2-4 hours before the increased flow gets the H2S under control. It can seem like a long time when you have the rest of the family staring you down
