When i bought my 375 l tank the plan was to change 40-60% once a week.. But, I now think about 30% twice a week is ideal??!!
It's the fish who tells me so! I feel they gasp to much between the waterchanges if I keep it to once a week...

you can never give your fish enough fresh water.....but you should run a set of tests weekly... that is a much more accurate way of telling when you need a waterchange ,the ammo should read zero...the nitrite should read zero, and the nitrate can go as high as 40 but i reccomend you waterchange when your nitrate hits 25 ppm ...weather it takes 3 days or 3 weeks for the nitrate to hit 25 ppm ...its at this point you should carry out a 30% waterchange....but you have got a new tank havnt you?????? so you may even be CYCLING!!!!!!!!......hope this helps:)

AnetteV wrote:


As has already been said your nitrate levels will give you a good indication of how often you have to change your water. The more fish you have, the quicker your nitrate levels will build up. The same goes for having a small aquarium. You have quite a lot of fish in your tank, I would imagine that your nitrate levels are quite high at the end of a seven day period. You should test for nitrate once a week, and ammonia and nitrite every now and then. It's normally fish behaviour that give you an indication that things might not be right with water quality.

Now we better address your fish gasping. They should not be breathing heavily. There are various factors that will make a fish breathe heavily. In many cases it is lack of oxygen in the water which is easily remedied. Firstly check where the water comes back into your tank from the filtration. Make sure that you have plenty of surface agitation. This will create oxygen in the water. If everything seems okay here, it may well be down to poor water conditions. If your nitrate levels get very high, the fish may well breathe heavily. They certainly will breathe heavily if you've got ammonia or nitrite present, although probably not until it reaches above 2.0. It is vitally important you check your water condition as soon as possible.

The tank is new, but not THAT new..
I just checked my water now. To much nitrate and nitrite.. Changing water as we speak.
Thinking I'll sell the Silver Dollar gang... It's the O's I love.. It's them who lives here. The SD are just renting space..

It is the nitrite that you want to keep under control more than the nitrate. It is thought that fish don't actually feel the effects of nitrate until it reaches 100 ppm. That doesn't mean that it's okay at that level, you don't want it rising above 40 ppm for too long. However, nitrite is extremely toxic and you certainly don't want your fish swimming around in water that contains this poisonous element. If you are having spikes of ammonia on nitrite, it could well be down to the amount of fish you have. You have got quite a lot of fish for your size of tank and I would not be surprised if that is causing your problem. I would definitely re-home the silver dollars. For the time being, reduce the amount of food you put in the tank. Maybe feed your fish every other day until you have got your nitrite under control. Don't worry, your fish will be perfectly okay

Sorry to change subject but is ok to feed small oscars once every 2 days? their about 4 inches now, because at the moment their eating once a day and sometimes twice a day.
i was told the feed them up when their young, but is it ok to do it once every 2 days?

while Oscars are growing very quickly, I would be inclined to feed then a couple of times a day until they reach five or 6 inches, then you can preduce their feeding to once a day. I wouldn't advise cycling at tank with the Oscars.

x2

only by testing your water will you know when and how much water you have to change. as previouly stated in a cycled tank check for nitrates every few days and when your nitrate reading hits around 30 ppm change about 30% of your water. keep doing this until you see the pattern develop then you will now how often you have to do water changes.
now since you have nitrites in your tank you should do about a 30% water change every 2 days until the nitrite reading hits and stays at zero.

hope this helps

so mush had been said, no more to say except the golden rule.
if you are not sure of your water quality, it wouldn't harm
your fish if have a water change. pristine water is the first
defense of fishes against any fish illnesses.

but if you are practicing heavy hydroponics, you can have your
tank in good condition for more than a year without water change.
(see posting at write a review "minimal water change")

Thanks guys!! Don't know what to do with out you!

Thanks, I'm sure I'm speaking for everyone when I say your comments are appreciated. That's what we're here for, to try and help people keep their fish healthy;)