Personally, I think that anyone concerned about the amount of water changes needed, should avoid the seahorse keeping hobby.
While some have seahorses that seem to do OK with smaller water changes, most do not and as the water quality degrades and nasty bacteria multiply, the seahorses end up with infections internally and/or externally. (there are NO test kits that can tell you when this water condition is occurring, thus requiring more frequent water changes and better husbandry than for a reef tank)
Seahorses, like people, have varying levels of resistance to sickness/diseases such that some have excellent capabilities to live in sub optimal situations, with some perpetually having problems, and most falling at levels between those two. My experiences have shown me over many years that most will tend to fall into the lower category rather than the high resistance grouping.
Unfortunately the odds are that you will NOT purchase seahorses that will have the best resistance, and, if you DO luck in, it may not be a condition that applies to ALL of the seahorses you may put in the tank.
I had sufficient losses in my early years to now know that I will AUTOMATICALLY assume they are low resistant when I acquire new seahorses and do the water changes and husbandry that I find provides the BEST chances of success.
I agree with the majority of this. I wanted to add that in 2005 to 2009 when I had 2 pair of H Redi they seemed to be bulletproof. Ate like pigs, consistent breeding cycles. Never could get fry to live much longer than 2 months but I was really into it.
I got a pair of captive bred Ingins in 16. Quarentine, deworming, Chiller, bare bottom tank, captive breeding shrimp that could be gut loaded with meds or extra fat. 110 gallon tall tank build just for them live rock, long break in period. I used a 20 Tall receiving tank to stabilize them and fatten them up. Ran it like my SPS reef except with way more water changes. I had no hesitation to throw money at the systems. They were a completely other story. It is like they were raised in a lab with immune system ever. Lost a pair. Tried again. Constantly dealing with some issue for them. Just generally feeble animals. Granted they are hard to keep, but it is not like I am new to this.
I had a pair of H Erectus that I picked up during the Ingin mess. They lived in a separate system. Much more hearty but still had their issues. The whole experience left me feeling like some captive breeders do a better job than others at raising animals that are ready to move on to home aquariums. Or some animals are just weak and you dont know what you are going to get.
I took a tour of ocean rider's breeding facility when I was in Hawaii in late 16. Not the best prices for livestock, but the setup there at least allows for natural selection to happen and some exposure to the elements. I have purchased from them, but if I keep seahorses again, I will get them from a place like that.
They are a labor of love and a person needs to be willing to do all kinds of things to keep them alive and healthy. If you are feeling like water changes are going to be a burden, you may want to give things some more thought. That said, I do have a 120 gallon reef tank that has a dragon face pipe fish, Mandarin goby, and dozens of other random fish in it. I have put in my research hours, stocked it with microfauna, and took my time letting things come together. I have been running the system without water changes since mid 2017. It is the healthiest tank I can remember owning. So yes, if you put in your research hours pay attention to your designs, send out for lab testing on a regular basis, you may be able to put a system together that will allow you to do fewer, or no water changes. As well as no, you can not expect to buy a pair of seahorses and have them live in a system that you don't want to do the maintenance on.
For what it is worth. 30 tall 24x24x12 and 60 cube 24x24x24 are my favorites for seahorses. I never go over 24" high because I cant reach the bottom without getting my shoulder in the water and that is just enough to make regular maintenance suck.
They are not that hard to keep. We all get a system to make water changes easy for ourselves and they are amazing animals.
Good luck.
