Just an opinion. I wouldnt add MH to a seahorse tank. I am currently spending lots of money to downgrade my lights. I recently upgraded my tank to a 120 Gallon with trickle and sump, built in refugium. I have a mixed coral tank with LPS, SPS, Leathers and Mushrooms. The system I purchased included Metal Halide lighting with T-5 with blue and white actinics. My corals loved it. My seahorses… well they went into hiding, and I have hated myself ever since. They actually tucked themselves under rock caves and hid in corners buried with plants. The tank looked barren. I removed the entire canopy and am in the process of reworking it. I have already purchased LED Moonlights at $69.00 ( to reduce the bright effects on dusk to dawn). as well as three timers @18.00 ea. (1 for the actinics to run all day , One for the halides for short periods daily, and one to control the moolights AM and PM) 2 new actinic bulbs with lower watts and higher Kelvin (to reduce the glare) @ $35.00 ea. Currently I am running a Power Compact and the babies are greatful. I am getting to enjoy them again. I missed the dances, and games they played, and for the first time I ended up fighting at meals noone even wanted to come out to eat. I target fed every meal while those lights were running. So I got to invest alot of money actually downgrading a system to satisfy my horses. The corals will have to live with it. Everyone is back to eating dancing and behaving normal with the new lighting system. Most of the mushrooms and leathers actually prefer the lower lighting some of the hard corals thrived with the higher lights but survived under the PC. Good Luck with your decision. Hope you dont end up spending more to downgrade after the initial upgrade cost.
Total cost to downgrade $193.00 plus tax, and I am not even sure this will work.