What % Water Changes?

Rate of water change is entirely down to your tank setup and your water. People may tell you that you MUST change 25% a week, but with heavily planted tanks and fairly hard water I change only 20% every 5 or 6 weeks without problems. If your pH is stable and nitrates stay within reasonable levels, then changing water every week for no reason seems a little ridiculous to me. I only do a larger water change before adding new fish, just to be sure nitrates are as low as possible.

Don't forget that Richard has very heavily planted tanks. He fits into the category 'plant tanks with fish', while I fit into the category 'fish tanks with plants'  You can only get away with his water change regime if you have heavily planted tanks.


And you only need one bucket, though I have 2 - a water out and a water in.

My husband is obsessed with fish tanks being dirty. I have to empty the 'water out' bucket down the drain outside, but I fill the 'water in' bucket under the tap in the sink. He would have a fit if I put the "dirty"  'water out' bucket in the sink - and now that he's retired, he'd catch me doing it 

I'd recommend that you read the article on water changes on the Thinkfish site (under "Fish articles"). Actually, all of these articles are very good and I'd advise any relative beginner to read them. I like the fact that they aren't too prescriptive but explain the issues very well.

Personally, if I were starting up a tank with relatively few plants, I would do more regular smaller changes, say 10% twice a week. Keep testing and if your pH stays stable and nitrates don't go too much above your tap water, then you can slowly reduce the water changes. I do think that fish are often better off in more stable conditions and that changes of more than 20% can stress fish to the extent that diseases can take hold, especially in some of the weaker overbred species.

There are exceptions, Corydoras seem to love larger water changes and usually get very excited. But then, they seem to be among the toughest of all fish. When do you remember anyone writing here to say "My Corydoras are sick/dying" as opposed to the numerous problems with guppies, platies and bettas?