Hi! I recently set up a secondhand tall 55-gallon that's had its sand and snails cycling for at least 2 weeks, and the fish are on their first week. The tank was not under my ownership while it was cycling, it was simply advertised as bioactive and ready to house fish. With guidance from other freshwater aquarists, we set up the tank with a 4-chamber filter and 2 sponge filters, a heater, a few decorations, and 3 live plants, vacuumed the sand at the bottom of the tank, properly treated our water before filling it up, and waited for the filter to clear everything up. When the water was clear and the snails were out, which was about 2 hours after setting the tank up, we added the fish and things went well. They've been in there now 6 days, they're still acting healthy and happy but when I checked the water parameters yesterday, the ammonia levels had suddenly spiked, which leads me to believe my tank is not actually properly cycled. I did a 30% water change around 10:00pm yesterday after discovering the ammonia was at 1.0ppm and used a double dose of seachem prime (recommended for my city's extra mineralized water) to treat the new water.
(as of last night, ammonia updated post-water change)
pH: 7.6
ammonia: 0.05-1.0ppm
nitrite: 0
nitrate: 0
kH: unknown
gH: unknown
tank temp: 78 F
The fish are acting normal, no new behavior; the mollies are exploring as usual, the algea eater is running laps on the walls (he's always been like that in every tank, we named him Nuts for it), the catfish is hiding, the shy cichlid is hiding and the less shy one is just leaving the others alone.
Tank inhabitants: 3 adult mollies, a school of around 10 guppies and up to 3 baby mollies, a Chinese algae eater, a striped Raphael catfish, 2 small striped black-and-blue cichlids, and a few mystery and cone snails.
There's 3 live plants, I'm unsure of the exact species but one is a short, rooted grass, another has tall, light green stalks with sturdy, wavy leaves that come to a narrow point, and another looks like a gigantic, fluffy, swirly pipe cleaner that has roots but floats at the top of the tank; the guppies and babies love hiding in it, and the mollies love eating it. There's also a little duckweed at the surface.
My best guess is that the tank was either not properly cycled when I got it, or I removed too much of the beneficial bacteria while cleaning the tank, either way the tank needs to cycle again and my fish are living in it. The guppies came from one tank and the rest came from another, both of which had elevated ammonia levels. The water in those tanks is not often tested, but during water changes you can smell some of the ammonia, so I at least know it's there and the fish are acclimated to it. Right now my plan is daily 30% water changes with the seachem prime and daily testing for ammonia, nitrite, and nitrate. The pH has been consistent, and the nitrate and nitrite levels have always been at 0. Is there anything else I should do to ensure the health and growth of my tank's ecosystem?
(as of last night, ammonia updated post-water change)
pH: 7.6
ammonia: 0.05-1.0ppm
nitrite: 0
nitrate: 0
kH: unknown
gH: unknown
tank temp: 78 F
The fish are acting normal, no new behavior; the mollies are exploring as usual, the algea eater is running laps on the walls (he's always been like that in every tank, we named him Nuts for it), the catfish is hiding, the shy cichlid is hiding and the less shy one is just leaving the others alone.
Tank inhabitants: 3 adult mollies, a school of around 10 guppies and up to 3 baby mollies, a Chinese algae eater, a striped Raphael catfish, 2 small striped black-and-blue cichlids, and a few mystery and cone snails.
There's 3 live plants, I'm unsure of the exact species but one is a short, rooted grass, another has tall, light green stalks with sturdy, wavy leaves that come to a narrow point, and another looks like a gigantic, fluffy, swirly pipe cleaner that has roots but floats at the top of the tank; the guppies and babies love hiding in it, and the mollies love eating it. There's also a little duckweed at the surface.
My best guess is that the tank was either not properly cycled when I got it, or I removed too much of the beneficial bacteria while cleaning the tank, either way the tank needs to cycle again and my fish are living in it. The guppies came from one tank and the rest came from another, both of which had elevated ammonia levels. The water in those tanks is not often tested, but during water changes you can smell some of the ammonia, so I at least know it's there and the fish are acclimated to it. Right now my plan is daily 30% water changes with the seachem prime and daily testing for ammonia, nitrite, and nitrate. The pH has been consistent, and the nitrate and nitrite levels have always been at 0. Is there anything else I should do to ensure the health and growth of my tank's ecosystem?
sounds like a great set up and a great size to get started with! 
