Protein skimmers suck on seahorses tanks. They do
They suck in water to work.
The correlation through purely ancedotal evidence on the relationship between HOB protein skimmers and GBDis real, and has not been disproven to my satisfaction. I conceed many of the studies by University's and PHD marine biologists don't seem to stand up to the scrutiny of the members of this site, but whatever.
Skimmers do remove certain wastes, but they also remove life that will be used as food, and directly compete with macro algaes.
Skimmers rob system of food = bad
Refugiums provide food = good.
Both reduce nitrates, and provide cleaner water. Anyways.
I guess if your not planning on keeping maro algaes, and are going with a shallow sand bed, as well as running the system without a sump, then I would probably run a HOB skimmer as well. I like the Aqau C remora. I use it on my 20g SPS tank, in the sump, it doesn't pull out much but I do have a 40g sump filled with macro . . . so. It is a good skimmer that produces very little micro bubbles if any at all.
I too am planning a 37g tank soon. I'm assuming from your lighting description your going with the 30" by 12" footprint. Lighting is a chore. I really like T5 lights for seahorse tanks since they put out so much light and burn so cool, but unfortunatley they don't seem to make a 30" T5 fixture. I do have a 30" satelite fixture in my garage. I liked it but it did produce some heat even with the exhaust fan and the mounting brackets keeping it a couple inches off the tank surface.
Liverock is my favorite filter, but I like to run mechanical as well. Look into the Magnum HOB cannister filter as it is a great filter with an outstanding reputation and gives you control over the media you use.
As far as the heater, i'd do a 50w. 74F is the recommended maxium temperature. Not the needed temp. If your keeping tropical species without corals 70F is fine. Personally on my horse only tanks I set the heater at 70F and leave it there. Seahorses will do fine at 70 and far lower. The lower temp is great for long term succsess. Cooling tanks is usually more of an issue then heating tanks for most hobbyists. As long as your not dropping below 68F for tropical horses I would not worry, even then if not long term lower temps are dandy.
I plan on running my 37g tall seahorse tank with many species of macro algae, a 25g sump with a "cryptic zone" like Tyree speaks of, a fluval 304, 40 lbs of LR, a 1" sandbed, an 18w UV and either the 130w satellite fixture or a 150w MH bulb. SHould be fun.
Did you register on the org yet? What's your SN.