I discovered over the past 6 months that it is actually possible to keep plants with goldfish. I always heard the goldfish would view the plants as a salad bar. I had visions of them raining destruction on the entire tank leaving behind a post-apocalyptic barren wasteland of a tank with bits of decaying plants floating around.
When I lived in Phoenix my 120 gallon tank was set up as a high tech planted tank with CO2 and Metal Halide lighting (2 175w). When we moved to Denver last year I wasn't planning on setting up my 120 gallon tank as a planted tank again, I wanted to use it as a giant shrimp breeding tank. My wife decided she wanted it set up as a goldfish tank so naturally I was overruled.
Despite my original reservations about getting goldfish, the tank quickly became my favorite. It is low maintenance and both my wife and I enjoy sitting in the room, watching the goldfish slowly swim around (or quickly if they being fed). If you have a big low tech planted tank and are looking for a large low maintenance fish, I would highly recommend trying some Ryukin goldfish. I would love to hear about your experiences with planted Goldfish tanks too so if you have had one before please leave a comment!
Tank: 120 gallon tank. I have the 5' version instead of the 4' or 6" version so mine is 60x18x26 (LxWxH).
Substrate: Primarily Eco-Complete with a little old lava rock mixed in.
Filtration: 2 Rena X3 filters filled primarily with mechanical filtration, one tray in one filter has some Ehiem ceramic balls for biological filtration. I have the spraybars on either side of the tank. pointing towards the center of the tank.
Lighting: I was using 2 shop lights but they were "ugly" according to the wife so I bought a 48" AquaticLife T5 HO Dual Lamp Light Fixtures which gives me 108w of light. Since I have a 60" tank the light doesn't span the whole tank but I have a glass top that the legs sit on and it works just fine. I wouldn't buy another 5' tank because they are so harder to find lights for.
Heating: The tank is in a semi unheated front room. Since we have a couple of Bushynose Plecos in the tank we wanted to keep the temp high enough to keep them happy. I use 2 200w Marineland Visi-Therm heaters and an Azoo Micro Temp Controller to control both heaters. I keep the tank at 70 degrees.
Fertilizers: None (other than goldfish waste).
Food: We feed two pinches of Saki-Hikari™ Fancy Goldfish Color Enhancing Formula every other day.
Fish: The tank has 5 Goldfish (1 Black Moor and 4 Ryukin), 4 Dojo Loaches (1 normal and 3 albino), and 2 Bushynose Plecos (1 Male and 1 Female).
Plants: I currently have some Java Fern, Willow Leaf Hygro, Anubias (both Nana and a larger variety.