Thanks Tahoe,
I'll post a bunch more pics for you.
The setup is a 39g pro from cadlights with a 12g sump. It's stock except the lights are t5 instead of halides and I've added a reef keeper, uv sterilizer and chiller and changed the overflow pumps to have less flow.
We had six seahorses for about a year and a half (tankbred from Ocean Rider) and they were doing really great, but we have had two die in the three months and are going crazy trying to figure out what's wrong. They died peacefully in the caulerpa, no choking, no visible signs of parasites or desease and they were eating just fine. We are going through everything in our tank but can't seem to find any problems. The readings are all perfect:
temp: 74f
Ammonia/Nitrates/nitrites: 0
PH: 7.8-8.0
Oxygen: 8
Phosphate: .5
Iodine: .7
There is practically no waste in the tank, since the seahorses have all learned to eat from the dish in the middle. The only pests in the tank are aiptasia and bristeworms, and obviously there is a lot of feather and grape caulerpa, but I haven't read about any of those affecting seahorses. I'm hoping they died of natural causes, but when we got them they were six months old so that would be a very short lifespan.