No Problem
More info:
1.)My plan was to keep them in the refugiums.
This is a very bad idea, although I understand why you thought a refugium would be a excellent habitat for a seahorse. Seahorses require a tank dedicated to them, a Species Only Tank. At least for your first seahorse tank. There are very few compatible tank mates for seahorses due to their slow eating and inefficient digestive tract.
2.)These hold about 20-25 gallons of water and have a flow of water that comes out numerous perforations in a PVC pipe. The refugiums have about 20# of live rock, a few small snails and blue legged crabs, feather dusters, macoalgae and three mangrove plants. Lighting is provided by a hanging MH over one and a T5 fluro with both actinic and 10,000K bulbs over the other.
Seahorses need a tank that is twice as tall as they are. For Horse species 29 gallon is the minimum for one pair, and that's pushing it. Ponies do much better in small tanks. The largest I would keep them in is a 15 gallon, this is due to the size of their prey(baby brine shrimp, and the size of the pony~adults are ~1 inch) Lighting is also different in seahorse tanks. Due to the need of low flow algae is your constant enemy. I am still trying to find a balance.
While I do not know the exact water flow thru the refugiums (I would questimate 400-500 gallons/hour. I do have a single Maxijet 600 to move water in each refugium. The sides of the refugium are 15" in height.
3.)They will not be keep with other fish/corals. They are separate in the DTs
There are seahorse friendly tank mates, but it is hard to meet the needs of the seahorse and the tank mates at the same time.
4.)I did not realize ponies=dwarfs
No problem, this was something I came up with to make the distinction between the two, and it's easier to type.
5.)What species of seahorse would be the most hardy in this situation regardless of size?
Unfortunately hardy and easy do not go along with keeping seahorses. But here is a link to a list of all species and ease of keeping that Darth helped me with.
https://forums.saltwaterfish.com/t/283300/care-level-of-seahorses
I'd like to hear about the current tanks you have, perhaps one of them could be converted into a seahorse tank, especially since your tanks are loaded with pods