lfduty -
I am going to apologize in advance if I have misunderstood you, as your posts are very hard to read and follow.
First, may I ask why you felt the need to add 4 horses to each "test" tank? Surely, a pair would have let you know what you wanted to find out.
Also, I am not arguing for or against you, but this has been my experience. I have had horses for over the past 5 years, in 5 different set-ups. My very first horse lived up until a bacterial infection took the tank in May. All of my set-ups have contained caulerpa, none of them have ever had a skimmer. My current setup has a large pump blowing bubbles thru a tube bubbler.
My caulerpa has often gone sexual, but never has it caused one of my tanks to crash. It has clouded the water to a point where I couldn't see thru the tank, but I never lost any livestock from it. I suggest you find what else killed your seahorses as I don't believe it was the caulerpa going sexual. That may be an inaccurate deduction.
Secondly, I have only had 1 case of GBD in all of my years of seahorse keeping. That horse was in a tank with absolutely no bubbles - no skimmer, no HOB filter - the only filtration was LR and a couple of powerheads. No matter what I did, that same horse kept getting GBD until I finally did a pouch flush, which seemed to cure him. There were 5 other males in the tank with him at the time. None of them ever got GBD. What I am getting at is blaming the skimmer on GBD may be an inaccurate deduction.
My tank currently has 2 tube bubblers in it, and has had since May. I added them to help dissipate heat, which they seem to be doing. I have not had any problems with GBD since adding them, thus proving that bubbles in a tank may not be as deadly to seahorses as originally believed.
My point is that there are many fish keepers out there who may have answers to questions from experience, and not just spout what they've read in a book. To me, your "tests" were redundant and inconclusive, and amounted to no more than 4 dead seahorses. If you didn't want people to suggest this, then you shouldn't have posted in a seahorse forum where people are passionate about their herd.