I do not know anything about seahorses aside from what I have read. From what I have read they will grow algae on them if the lighting is high because they are very sedate. I am sure one day people will figure out that I am the king of links if not first hand knowledge. So here we go: http://www.geekydweeb.net/seahorses.html GREAT home page of a fanitac. www.seahorse.org
And there is a board dedicated to them over at reefcentral.
I would doubt that it would hurt them, but a search of those pages may help.
Janet,
As I'm sure you have noticed, seahorses "ain't" the fastest animals on the planet
It is not unusual for some of them to grow a little algae on them. It is not harmful and will not impede them. If you find it unsightly you can always get a very soft toothbrush and gently rub it off under water in the tank. http://community.webshots.com/user/_starcar98
Ray
Thanks for the input. I did not think the algea would hurt them but thought I would put it out there. Yes, I have noticed my horses are not the fastest things in the world. Think I will forego the toothbrush idea.