Just as an update, I got the cyano
under control by adding a couple smaller Maxi-jets deep in the tank, which do not seem to bother the horses. My temperature is now steady at 73 degrees after replacing an old maxi-jet that was throwing some serious heat.
I did have a problem with my male. He stopped eating and began to lose weight pretty quickly. I gave him a freshwater dip, which he handled really well. Doing some research, I found that seahorses tolerate freshwater dips much better than most fish as long as ph and temperature match. Unfortunately, I did have to follow it up with a formalin bath, which seemed to solve the eating issue.
I switched from Hikari mysis to PE Mysis and I've seen a real improvement in eating habits in general and the weight of all the horses (and my mandarin).
My male has given birth 3 times and is working on his 4th brood.
Everything seems to be going well and I'm really enjoying these little guys. Unfortunately, my flatworm population has officially reached plague proportions and simply siphoning them out is not keeping their population down. I'm probably going to have to move everyone out to a QT for a while and dose with Flatworm Exit. They are getting out of control.