Question about water changes .how much and how often should i do it ???

Question

i have a 90 gallon tank with 2 small albino oscars and 2 plecos i know that i should do water changes but im not sure how much and how often

Answer 1

You should remove 20 percent of the water (about 18 gallons) every 1-2 weeks and replace it with new, fresh, dechlorinated and dechloraminated water.

Answer 2

I can see why this forum, and no offence intended to the good answers in here, causes more harm then good.  To get a consensus on this question is going to be difficult.  I'll tell you what I think, and in the end you're going to have to decide in your mind if what I say makes sense and you agree with it, or you agree with someone else.

First though, just because you have 2 plecos in with 2 Oscars does not make you overstocked.  The 90 gallons for Oscars is simply a matter of space.  Waste output will be high of course, but filtration is what copes with that, not so much the tank size.  Of course, will waste output matter if you have say a 20 gallon or a 500 gallon tank?  Of course, but we aren't going to that extreme here.

I keep and breed Africans, and currently I have six different breeding species.  I change my water out, at a minimum of weekly.  I feel very bad for them if I go longer.  What you will want to consider is a tank is a closed enviroment.  Tropical fish we all keep evolve from natural settings and in natural settings, water is always filtered and there is a constant renewing source of fresh water.  The only way a tank gets that kind of relief is from you the keeper.

Some people will tell you stories about how they've kept stockings not normal and how some even never change the water and no fish die.  How do we explain how a smoker can smoke all their life and not get cancer, but someone could smoke a month and get cancer?  Doesn't mean because something did work, that it should be done.

IF I were you, I would be changing anywhere between 30-50% weekly.  Yes you can actually change the water out too much.  If you start changing out more then 50% at one time, you run a higher risk of drastically altering your water chemistry which is not a good thing in most cases.  You can do smaller changes and frequent ones at that, but to me, this becomes time consuming.  I however keep five different tanks running, and if I had just one tank, maybe that would work better.  One of those cleanings though, if you do frequent small ones, you'll need to vacuum in the substrate though.

If you have anymore questions or need additional input, feel free to post follow up or email me.

Answer 3

Albino oscars are a large fish and the more you have them more mess. I should know i have 4. Have had for 6 years now.

I change the water every month or when it starts to go grotty.

I change about 20-25%

Don't forget to treat the new water with chemicals from pet shops to get rid of toxins and make tap water safe.

Hope i helped

Answer 4

20% water change a week  

Answer 5

I change my fish tank water 20% 1-2 times a week.

Answer 6

Well, just for 2 oscars you need a 100+ galon tank, but with the 2 plecos thrown in, your tank is overstocked. Since it is overstocked, do water changes twice a week. after it is cycled you need to do twice daily water changes.

Answer 7

The more often, the more consistent your water parameters will be.

The more water, the cleaner it is. Don't worry too much about lose good bacteria, as most the good bacterias are in your filter, and they live on objects' (gravel, ornaments, etc) surface, no in the middle of water.

90g.. is quite big.  In normal circumstance, i suggest you 15% water change per week.

Larger and more often is always better, but probably unnecessary and quite tiring.

Answer 8

Oscars are pretty messy fish, and although they are small now...they will quickly grow. By keeping their water clean now, you will not only help them grow quicker, but will also help ward off potential health problems they could have as adults. Be aware, that as Oscars age, they can get aggressive, you may need to re-home one of your Oscars down the road, or invest in another tank.

your tank is pretty much maxed out, if not right now (as your fish are babies) but they will grow (dramatically) and max out your bioload. Although it may look like you have plenty of space now--resist the temptation to purchase more fish.

As for water changes, you could probably get away with doing 10-20% water changes weekly right now, but once your fish get beyond the 6-7' line, you should up the water changes to 25-50% weekly.  

Answer 9

If these are the only fish in the aquarium, you can get away with every 2 weeks.  Doing water changes often will help prevent a build up of waste and ammonia in your tank.  This will allow for faster growth in your fish, and healthier fish.

It's recommended to do a 25% water change, using aged or dechlorinated water.

Answer 10

No problems with overstocking right now. Eventually it may get a bit crowded in there, but thats a potential future problem.

As for water changes, there is no ONE correct answer for every tank. But I suggest you do weekly water changes, 10-20% is probably all you need to do at the moment. As the fish get bigger you may need to step that up to 50% per week.

But test the water for Nitrates, there are other pollutants that build up in the water too, but nitrates is the fastest one. If you do enough water changes to keep that below 30ppm then your tank should run well.

Exact amount depends on YOUR fish, how much they are fed, and even the quality of your tap water. If you aren't sure, change more water, it will do no harm. Not changing enough will cause problems.

Ian

Answer 11

I would change about a quarter of the water every couple of weeks or so, and only do a full water change every 6 months to a year.

The best thing to do is monitor the levels of ammonia, etc in the water to ensure that the water in the tank remains healthy for your fish. If there is a problem with ammonia, etc then i would change the water more regularly until it sorts itself out.

p.s. don't forget - don't just use water straight from the tap - always use something that will make the water safe for your fish ( I use 'Tap Safe'), and i recommend that you leave the conditioned water overnight so that it can reach room temp. (which is probably roughly the temp. in your tank).

You can also buy special products which help keep your tank healthy, and reduce the need to change water so often.