About Christy Expertise I can answer some questions regarding freshwater fish ranging from their care to diagnosing common diseases or problems with the fish. I can also answer questions regarding the care and maintenance of an aquarium. I haven't had much luck with live plants, so can't help in that area very much. Not real good with explaining salt water or brackish set ups too well either. Also regarding goldfish, I have some comets, and have a little experience with them but mostly just general info on them. I AM NOT THAT FAMILIAR WITH ANY OF THE FANCY VARIETIES OF GOLDFISH. YOU MIGHT BE BETTER DIRECTING THOSE QUERIES TO AN EXPERT MORE FAMILIAR WITH THEM. If I can't answer or don't know something, I'll let you know, so don't be upset if I reject your question, I'll always explain why. I would just rather not answer then give an answer I'm not confident about.
Experience All personal, first hand, general fishkeeping experience. I've had fresh water aquariums now for about 7 years. I've had tropical/community fish tanks, African cichlids, South American cichlids, brackish water puffer fish, and a lot of other varieties in between.
Education/Credentials None, all personal experience
Question I have a 150 gallons tank fresh water and 11 fishes middle size inside,six silver dollars, one geo, one severum and three small plecostomus. I would like to know how often I should do the 1/3 change of water. The fish store told me once a month do 20% water change, but it seams it will never be a established tank changing that often, I was told another time I can change 1/3 of the water once a year, a lot of different information.
I would like to understand better and to know the right thing to do, why to change or why not to change.
Thanks a lot!
Answer Hi Andrea
Doing partial water changes doesn't affect the "establishment" of the tank. It can prolong the cycle process a bit in a newly set up tank, but it won't prevent it from cycling-unless you're doing 100% changes every few days to actually remove the ammonia so it won't cycle.
You do have a large tank, but I always and still recommend doing water changes/gravel vacuums once a week, changing out about 20-25% each time. And that's for a normal stocked tank. When you do water changes, it's also adding minerals back into the tank that the animals, fish, and plants need, and those get depleted in the "old" water. It also keeps your nitrate levels down. Once a year-that's insane! That is just setting up for a major disaster. Even once a month isn't good. The nitrate levels in the tank will sky rocket. At the very least, you may be able to get away with every 10-14 days. The best way to check, get a test kit(should have one anyway), and test the ammonia and nitrites-which should always be at 0 ppm in a fully cycled tank, and nitrates you want to keep under 20 ppm. If after 7 days, the nitrates are going higher then that, then go with the 7 day schedule. If they test fine until 10 days, then go with the 10 day schedule. Every tank is set up different, and has different things going on in it, but like I said, the rule of thumb I use is 25% once a week. Can't go wrong with that recommendation :) Take care of the water, and the fish will basically take care of themselves-they won't get stressed from poor water quality, which is what causes diseases and infections.
