Dead Seahorse question?

I have to agree with both posters. Nonetheless, I will not yell at you. You just made a mistake and it happens to the best of us. But here are some pointers if you decide to continue with seahorses, which I wouldn't until you have at least 5-10 yrs under your belt. They are fragile, so fragile that anything that is off so to speak can kill them. First thing I will say is you do not add a seahorse unless all parameters are great, not just good. The tank should be cycled for at least a year or more. They are not like other fish that will bounce back after adjusting parameters, they go into shock easily. Now for the whitish spot, that means that they were constipated and probably infected with a bacteria. Seahorses do not have stomachs, all they have are intestines from the top of the belly down. So they process food quickly. But they can easily become backed up so to speak. I would feed with amino omega, it helps with this ailment. Your PH was way too low, they have to have a PH of 8.0 or higher. Ammonia has to be 0, nitrites 0, nitrates between 0-5, calcium at least 400 seeing how their bodies are exoskeletons. Also Mg, Iodine, and DKH has to be in perfect match or they will die. The reason one was stuck on the filter was because he died and rose to the intake of your filter and became stuck. Now here are some husbandry notes, feed three times a day with garlic extract and amino omega soaked mysis shrimp. feed with something that releases small amounts at a time, you do not want to rise nitrates, feed only what they will eat. They are slow eaters so that is why I say this. Keep a QT handy, you will need it to treat for all diseases. Do not over load the tank, anything that raises ammonia will straight up kill them. They really need a wet/dry filter, canisters cause vibriosis, a horrible disease that is fatal, no coming back. If you do use a canister you have to clean the tubes everyday. They need hitching posts and places to rest. NO HERMITS! they will pinch them and cause infection. Star fish only for bottom feeders. Do not buy kelloggies unless you have 60 gallons or more, and do not buy kudas or erectus unless you are very experienced with sea ponies. The black seahorse is your best bet, they are the hardiest. Also keep cochepods in the tank, they love to munch on them, you can get them at the LFS. I am sorry about your ponies, and I hope I helped. I do not like to be mean because we have all made mistakes. Just learn from this one. Also go to www.seahorse.org they will walk you through everything. Good luck!