I was hoping some of you might be able to provide a little guidance. I took on a tank from a coworker of mine who had felt overwhelmed with the day-to-day care involved in having seahorses. Unfortunately the coworker made some bad choices in her initial tank setup that I'm hoping to correct. So I'm having a few problems I was looking for help with. Since I got this tank I've been budgeting to upgrade to a larger tank for the seahorses. My coworker placed four erectus in a 15 gallon aqueon column tank. On this tank is a Fluval HOB filter, a heater (which I don't really use at the moment, the tank naturally stays about 70 or 71 degrees in my house), a small protein skimmer and an airline tube open with no air stone. It has a sand bed made up of live sand and black aquarium sand. I took on this tank in May and have since been saving to buy a new one. This weekend I planned to buy a new 50 or 55 gallon tank that has a sump, built in filter, etc. I'm hoping this could make a better home for them. Unfortunately, i can't really afford to go any bigger right now. There are two females and two males, one male I believe to be pregnant. I was hoping to use the 15 gallon column as a grow out tank should they breed. I was planning on posting here to ask a few questions about the tank upgrade, including what would be the best of the best for these guys regarding a filter, protein skimmer, and lights in a tank of this size, whether I'd need to cycle the new tank for 6 weeks before moving the horses, or if I used water from the previous tank if I could move them sooner, and any other suggestions you might have to make this tank great for them. Then a problem popped up this week. All four are active and great eaters. They eat enriched PE Mysis twice a day, 6 days a week. Yesterday, out of the blue, this beautiful white female seemed like she was having trouble hitching. I noticed a small white bump on the outside back of her tail, about halfway down. It has a pinkish hue around it. She would swim around but just lay on decor/plants/the ground. Today she's stopped eating and her breathing is becoming labored. I tried to research what to do online but I come up with an overwhelming number of possibilities and treatments. Upon closer look, I think another bump is rising near the other. I would like to know a few things. Should I set up a hospital tank? This is a seahorse only tank with the only tankmates being nessarius, nerite, and cerith snails. Should I treat the whole tank in case whatever she has is contagious and the other guys may have it too? Should I buy the new tank? Should I transfer the three and use the 15 gallon as a QT for the sick female? I do weekly water changes with RO/DI water because of the small tank size. Currently my pH is a 7.8. My ammonia and nitrite are virtually 0 and my nitrate is around 5.0 to 10 ppm. My salinity is 1.022. I tried to take a pic of the bumps but I couldn't get a good view of it where she's laying. If there's any other information you need, let me know. Any help you could give would be much appreciated.