Marty,
To effectively do a hyposalinity, you need a refractometer. The swing arm salinity meters are not accurate enough. Here's a page on the hypo treatment:
http://www.petsforum.com/personal/tr...osalinity.html
I would skip the FW dip, and use water from your main tank in your H-tank to reduce stress on your fish. Keep your main tank free of fish for 6 weeks to get rid of the ick there before re-introducing the fish in hospital. You may have to do top ups a few times a day during hypo treatment to maintain the low salinity levels. Watch pH and alk as well since you are dealing with water with about half the normal alk.
On another subject, if you are going to get seahorses, please make sure you get captive bred. Here's the best SH site to do research:
http://www.seahorse.org/
Here's my own pages on our captive bred H. whitei seahorses:
http://www.lostmymarblz.com/hh-bw-28gal-whitei.htm
More seahorse pages and a gallery of seahorse feeding stations:
http://www.lostmymarblz.com/hippocampushaven.htm
HTH
