I am not Frank but do have several years of seahorse experience. Just got back on line after a break and found this post.
Can you post a pic of the tails to help with diagnosis and plan of care. This will also help others identify tail rot.
Tail rot needs to be treated in a separate quarantine/hospital tank with antibiotics. Melafix/primafix are not recommended for this disease process. You cannot add antibiotics to your display tank as you have corals/macroalgae. Neomycin/sulfa based medications are your first choice. Kanamycin, nitrofurazone or maracyn-2 are other alternatives. Must treat with antibiotics for at least 7 - 10 days even if symptoms disappear before then. If the area on the tails becomes an open ulcer, a product called biobandage can be used.
The addition of beta glucan to the food is a must to boost their immune systems. If they have gone off frozen food, try enriching live brine shrimp with beta glucan. I would feed beta glucan at least once daily for several weeks.
Lowering the temperature of the hospital tank to low 70's may help by slowing the bacteria's growth down as well.
Here is another thread on tail rot:
Best of luck.