Thank you so much! I am so glad that other people appreciate this tank!

I'm honored that my tank is an inspiration for you!
Right not I am using an old 20" Coralife 96W quad powercompact fixture. Its not ideal, but it came with the tank which I bought used from a member of my local reef club. I've been saving up and in the next month or so, I will be buying an LED fixture to replace it. My plan is to get the Maxspect Razor Nano 10000K fixture for this tank. The Coralife fixture works great and is plenty of light, but it runs very hot so I have to have two cooling fans on the tank to keep the temperature at 72F. Its also expensive to replace the bulbs on this fixture. Finally, it can only just all turn on and off and once and the drastic lighting change seems to bother the seahorses a bit. The new fixture I am getting will be able to do a gradual sunrise and sunset so that its not just a sudden change in lighting.
There are definitely several considerations with keeping seahorses and coral in one tank. First off is compatibility. You can't keep seahorses with any corals that are sticky, have powerful stings, or are capable of eating slow moving fish. Pretty much all LPS corals and definitely all anemones are not compatible with seahorses. SPS corals can't harm seahorses (except the fire corals), but the seahorses will hitch to them frequently and most SPS corals are too sensitive for that and will lose flesh and end up dying. With seahorses, it is best to stick with softies, macro algaes, gorgonians, zoanthids/palythoas, sponges, etc. Of course there are a few exception. For example, I have some porites (SPS) in my seahorse tank. They don't branch like many other SPS, so the seahorses can't hitch to them and irritate them.
Here's a great compatibility guide for seahorses:
http://www.seahorsecorral.com/Seahorse_Tankmates.html
The other thing to consider with putting corals in a seahorse tank is their flow requirement. It is outdated thinking that seahorses need to live in super calm, almost stagnant water. Your seahorses and your tank will be much healthier with a brisk, moderate water flow. You don't want blasting flow to the point that your seahorses won't let go of their hitches though. Basically, its best to have good moderate flow and set it up so that there are some calmer areas in the tank with low flow where the seahorses can rest. This effects the corals you can have because you can't keep any corals that need super high flow, like some SPS corals. However, most moderate flow corals will do great. Then you can find some corals that only need low flow to put in the calmer areas.
In terms of tank parameters, here's about what they usually are:
Temp: 72 F
Specific Gravity: 1.025
pH: 8.0
Amm: 0
Nitrite: 0
Nitrates: ~5
The seahorses are messy eaters and have to be fed frequently, so this tank needed good filtration to maintain good water quality. I have a skimmer rated for up to 55 gallons on this tank, a media rack with Chemipure Elite, Purigen, and Phosguard, and I run dual media reactors - one with carbon and one with GFO. I also have a bunch of macroalgaes in the display portion and also in the refugium chamber to help with fixing nutrients. I do a 15% water change every week, or twice a week if needed. Since I do frequent water changes, I don't test for or dose Ca, Alk, Mg, or any of the other trace elements.
This tank is a balance of keeping the nutrients in the system low enough to provide good water quality for the seahorses, but having some nutrients is good because the sponges, macro algaes, and NPS corals in my system filter feed off the nutrients in the water. I also made sure this tank had a very good cleanup crew to eat any leftover food from the seahorses, so it can't decay and mess up the water quality. I've got a lot of snails of different types, hermit crabs, and 3 nano serpent stars which do a great job scavenging for uneaten food.
I hope that helps!