How much and often do you change your water and why?

Question

I've always gone by 10% per week. I base this on nitrate and phosphate levels in the tank and overall cleanliness. I've seen a lot of people on here that do 20-25% per week. Why so much? What is your water change amount based on? Can you also include some data in your answers such as what your nitrates and phosphates are before and after your water changes? I would really like to compare other peoples data and maintenance to my own.

I guess I should expand more. I'm not asking what is right or wrong I'm just curious as to what works for you and why you do it that way.

I still change mine even though water tests are normal since most of my tanks have corals and the additional saltwater helps replenish trace elements, calcium, and other essentials. Also it helps keep my skimmers from going into overload from excess gunk from the corals.

I have never messed with small tanks but I would assume they need larger more frequent change outs especially if they don't have adequate filtration.

Answer 1

For gold fish, I'd do 25% a week, every week, because they are messy. For most tropicals I do 25% every two weeks. If I owned Discus, I'd do 10% every 3-4 days, because they are sensitive to less than perfect water and abrupt changes.
My nitrates tend to be about 20ppm before changing and 10-15 ppm afterwards.

Answer 2

With your added info I'll assume you are talking about water changes in a saltwater tank with corals and inverts. I don't currently keep such a tank although I did for many years. At that time I did 20% changes each week to replace expended minerals etc and to remove accumulated waste. I didn't have a protein skimmer for example, so the changes were needed to eliminate the potential for build up. Things have change significantly in filtration methods and materials since that time as well as in salt mixes and supplements, so I doubt that would really apply to a tank today unless you were using the same methods I was using them. If I were to be starting a reef style tank today, I would be doing the same research you are. Hope you find your answers, there are some good reef tank people here as regulars that can probably provide some of the data you desire.

MM

Answer 3

If you are testing your water and finding acceptable levels, and your water is clear, then you don't need to change it. It depends on what type of fish you have, the number of fish, the size of your tank, and how effective your filter is. I have an Oscar, and his poop is huge and gross, so I usually have to change about 40% every two weeks. I have a $300 dollar filtration system though. Without it, I would be changing water once a week. As far as N / P levels go, I have never, ever tested my water. I know thats a no-no as far as fish people are concerned, but I have never lost a single fish. Currently I have a 90 gallon with the oscar, a jack dempsey, a male and female convict ( breeding constantly ), two medium plecos, and a four inch algae eater. Despite numerous people saying those fish wouldn't work in that size tank, they are happy and have been for two years. The oscar and dempsey are buddies! I was told the dempsey would need 50 gallons for himself, or he'd attack everything, but he's the most passive fish in the tank. If you are running tropicals, they are much more hardy than you may think. I'd say just keep on at 10% if it's working for you. As long as your fish appear happy and healthy, you probably won't have a problem.

Answer 4

I do about 25% of the water once per week, and sometimes twice. I don't bother measuring phosphates, but my nitrates range from 10 to 20, sometimes even less.

I do this because clean water is a healthy thing for fish no matter how you look at it, and even with this clean water it's not clean like in the wild. Also, keeping up with tank maintenance means the tanks stay clean and never need to be torn down for overhauls.

Also, changing water not only removes old water with nitrates, phosphates, etc., but it introduces fresh water, clean and revitalizing the tank with nutrients used by the fish. Also, if I ever need to do a huge water change, or quickly move the fish to a new tank with fresh water, I feel safe knowing they're going from a tank already fresh with no worry about shock or acclimatizing.

Answer 5

The frequency of weekly water changes greatly depends on your tank: size of the tank in relation to bioload (how many fish/how much food is put in). For example, if you have 1-5 2" or less fish in a 55gal then the frequency of your water changes would be less than another aquarium that has 10+ fishes.

Answer 6

On my small betta tank I do a 50% water change per week. He spits his food out at the bottom quite often so it takes that much time to get the gravel clean with my gravel vacuum. : ) Some fish, like goldfish, are kept in small aquariums need more water changes.

Answer 7

You should only change water in your aquarium if there's a problem. I usually only wind up changing mine if I feel I really need to vacuum the rocks (about every 2-3 months). When it comes to aquaria, if it ain't broke, don't fix it.

For those of you who gave this answer a negative rating, my information comes from the manager of a pet store who has several large aquaria in addition to the ones in his shop. Also, I've had my aquarium for about 5 years and haven't had any problems.

Answer 8

once a week
because i have to