Dwarf seahorses are not compatible with the standard. I researched both when I first got into it and decided the daily hatching and enriching baby brine shrimp was too rigorous for me to keep up long term. It seemed to me that the cost of the set up would be significant less but the daily commitment of feeding and tank maintenance would be much more. Dwarf seahorses only need a small tank, a 5.5 gallon aquarium works well with an open airline tube or sponge filter with some artificial plants. However they need frequent water changes to keep up water quality from heavy dense feedings of bbs 3 Xs a day. Also if you go away you need to have someone trained to also hatch, enrich and feed your dwarf seahorses.
For those reasons I elected to go with h erectus, a standard specie known for being more hardy. My initial set up was substantial but I have corals instead of artificial decor and that required reef lighting and a chiller, (2 rather expensive pieces of equipment). Still you need a minimum of a 30 gallon tank for 1 pair of seahorses. Although not necessary, a good oversized protein skimmer is a very worthwhile investment. You need a filtration system that won't trap detritus or be extremely disciplined about keeping it clean so dangerous bacteria can not get a foothold in the tank. Seahorses succumb to bacteria more readily than other fishes. For that reason I stay away from filter pads and filter socks unless only used temporarily to capture debris when I do a deep clean. Even the standard seahorses should eat a minimal of twice a day. True captive bred seahorses are the best choice but sometimes lfs label seahorses captive bred when they really are not. Seahorse Source is an excellant place to get true captive bred. Also Ocean Rider has true captive bred but they are more pricey. Both of those have healthy robust seahorses that are trained to eat frozen mysis. This is only a portion of the things you should know before embarking on keeping seahorses. It's heartbreaking to watch them perish if their needs are not met, (I am speaking from experience) so do your research ahead of time to determine if you really can make the commitment necessary. Rayjay has some good information on seahorses under, My thoughts on keeping seahorses. Also Ocean Rider provides a free online course that is very extensive and informative. I would start there.
