Hi, I have been keeping marine followed by reef tanks for 20 years. But my daughters have decided they want Seahorses. I started researching but like everything else there are always varied opinions. Ideally what I would like to do is use a 20long tank tapped into a sump for my reef system. I realize a 20l is not very big and not very tall. But it is already in the wall in my girl's playroom

Beside size my other problem is temperature.However ORA says the species they are raising " are best kept in a small (10-20 gallon) aquarium by themselves". and "temperatures range from 75-85 degrees" Going by this a pair should be happy in my 20l and my reef temps would be fine.
My problem is that every other site I have found lists cooler temps, lower salinity, and needing more space, especially depth.
So any opinions? Recommendations?
Thanks in advance,
Ron