When to do a water change?

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DragonChild

Aquarium Advice Regular
Joined
Jan 13, 2004
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Okay, yes, I have had this tank set up since October 2003, but I don't know how often I should do a water change. I usually do between 25-50%, usually closer to the 25% mark. I do this about every month to two months. Is this too often? How often should I do water changes?

TIA
 
First thing, your water changes need to be more like once every week to two weeks, not months. You should be doing a gravel vaccum and about a 30-40 percent change.

Going that long with cause your water parameters to get all high, which can kill your fish first of all. Nitrate buildup will cause your fish some stunted growth... Ammonia can burn the gills of your fish...not good things.

My advice, up them to about once every week or two, I do one every other Sunday..
 
I do a 30-40% water change every week. But mine is a real small tank , so it needs it. for a 40 gallon do about 30% every week or two
 
Devilishturtles said:
First thing, your water changes need to be more like once every week to two weeks, not months. You should be doing a gravel vaccum and about a 30-40 percent change.

Going that long with cause your water parameters to get all high, which can kill your fish first of all. Nitrate buildup will cause your fish some stunted growth... Ammonia can burn the gills of your fish...not good things.

My advice, up them to about once every week or two, I do one every other Sunday..

I'm gonna disagree with you on several points.

1st, You only gravel vac CC. Not sand. Sand is highly preferred over CC because it does not trap the detritus the way CC will. And thats not even mentioning the filtering aspect of sand.

30-40% weekly is way over kill. 25% semi weekly or 10-15% weekly is more than adequate.

As far as--
Going that long with cause your water parameters to get all high, which can kill your fish first of all. Nitrate buildup will cause your fish some stunted growth... Ammonia can burn the gills of your fish...not good things.

An established tank will be able to maintain normal levels of both of these toxins. Water changes are designed to export heavy metals other such DOC's that are not broken down during the normal cycle of the tank. Barring excessive over feeding, or the death of a fish, the levels should never get at a level that the bacteria cannot handle. (provided it is set up properly and stocked properly in the first place.) Water changes also import vital nutrients for corals.
 
Smaller, more frequent water changes are preferable to larger ones. The bigger the water change, the greater the change in overall water chemistry. Big changes in your tank (regardless of source) are what causes stress and makes fish more vulnerable to disease etc.

I do a 10-20% change every week. This depends on how messy the tanks are. You'll want to gravel vac about half of the tank whenever you do a water change as well. You only do half so that you don't disturb too much bacteria. I didn't read that you have sand, but if you do, hover the gravel vac above it to pull up the bad stuff sitting on top and make sure you stir it around a little with your finger or something in order to aerate it.

If your tank is cycled you shouldn't see any ammonia or nitrItes unless something is rotting in your tank (food or dead fish). In one weeks time my tank will have about 20 ppm nitrAte. Two weeks will put it at around 30-40 ppm nitrAte. High levels of nitrAte are toxic to fish. Most people that I have spoken with don't let it get over 40 ppm.
 
I have to agree with deli_conker. A large water change can be bad for some fish. Some of the smaller exotic dwarf plecos may not like a 50% water change. I check my parameters every week and change enough to keep my nitrate non-toxic. I change about 15% every week or two on my 60 gallon tank depending on the population of my tank. I have a HOT Magnum canister filter that I use to vacuum my tank once a week and then do a water change. When vacuuming I just put in the micron filter and dump out what ever it catches when I’m done. The HOT magnum is super easy to maintain and makes a great supplemental filter for any tank I can’t take credit for that idea, I read it somewhere on this forum.

What really determines how often you should do a water change is your bio-load. If you are above capacity and have messy fish or feed them too much, you should be doing more frequent changes. My smaller tank contains only fry and takes a long time to build up toxic levels of nitrates, so I change the water once a month.
 
Hi Dragonchild :D . Another good topic. I'm going to say that all of the advice given here is good depending on the tank in question. My personal feeling is depending on the species, a 50% water change does a lot of good. Tell us more about your tank, fish and filters and we'll be able to suggest a water changing routine that makes sense.
 
SquishyFish said:
I'm gonna disagree with you on several points.

1st, You only gravel vac CC. Not sand. Sand is highly preferred over CC because it does not trap the detritus the way CC will. And thats not even mentioning the filtering aspect of sand.

30-40% weekly is way over kill. 25% semi weekly or 10-15% weekly is more than adequate.

I didn't see where sand was being used in this tank or crushed coral. I assumed, like most people with freshwater tanks, that gravel was being used as the substrate. Guess I overlooked that. But with gravel, I agree should be vaccumed every week (I do a sparse vaccuming of my whole gravel bed).

As for 30-40% that is what I do every two weeks, and is the message I tried to convey, not every week, my fault there.

As far as--
Going that long with cause your water parameters to get all high, which can kill your fish first of all. Nitrate buildup will cause your fish some stunted growth... Ammonia can burn the gills of your fish...not good things.

An established tank will be able to maintain normal levels of both of these toxins. Water changes are designed to export heavy metals other such DOC's that are not broken down during the normal cycle of the tank. Barring excessive over feeding, or the death of a fish, the levels should never get at a level that the bacteria cannot handle. (provided it is set up properly and stocked properly in the first place.) Water changes also import vital nutrients for corals.

True, I agree here. But what if, like many people who set up freshwater tanks, the tank was not cycled. A regular gravel vaccuming and water change here would play an important part in keeping fish alive. And, I can't comment on what you wrote about the coral and sand, a whole different ballpark for me :roll: I'm a freshie, lol.

But, I'm gonna agree with BrianNY, all depends on the size of the tank, what inhabits it, and many other things. Good luck!
 
BrianNY said:
Tell us more about your tank, fish and filters and we'll be able to suggest a water changing routine that makes sense.

I have a 40 gallon tank, housing a pleco (about 3-4 inches long), a red-tailed shark, and right now, a mickey mouse platy. I am going to add some more tetras and platys as soon as I find out what caused the tetra genocide. I have an Aqua-Clear 200 HOB filter, a hagen heater, an Azoo air pump, with a stone in the corner and a bubble 'wand' throughout the tank. I leave the light on between 12:00 noon and 9:00 pm, and have gravel in the base of the tank, probably about 1 1/2 inches. I vacuum the gravel when doing the water change. I suction the water into a 5-gallon trashcan (purchased and used ONLY for this purpose, washed out super well). I water the garden with the water, and refill from the bathroom faucet. I add Jungle Start-Right Crystals to the water to remove impurities, and check the temp to be around the same as the tank. I pour the water over the ship display to avoid disturbing the fish and the gravel/decorations.

I feed 1 algea wafer to the pleco every 4 days, and feed the others about the same time. I have to break up the food a bit, the tetras couldn't eat the big flakes. I turn the filter to low to avoid 'sucking up' the food as soon as it gets in the tank. I have 2 sticky thermometers and a suction cup one, and I think that it all there is.

*whew* That good enough?
 
I agree with this previous post. I think a 200 gph filter is not enough for that tank. I have a 38 gallon and ended up with a Penguin 330. I don't think it would hurt for me to even 1 day add another filter if my bioload gets larger with the eventual barbs I plan to add. Having only 200 gph flow will limit to a point your max bioload.

As far as water changes go, I do a 5 gallon change every other week, and a 7.5 gallon water change every other week. So basically, 5, 7.5, 5, 7.5, etc. This works out to 13% and 19% every week. I no longer concern myself too much with ammonia or nitrites in this tank as they have not registered for the last 5 weeks (I still test weekly). With those water change percentages, my nitrates have never broken 20, so I think I have found a good maintenance schedule. I have broken my tank into 4 sections, and every week I vaccuum 1/4 of the gravel. This way every month the gravel gets a good thorough cleaning without disrupting the bacteria in the gravel too much.

That's just what I do,
Paul
 
:D Excellent post Paul. Dragonchild, you can follow this routine to assure a happy healthy aquarium.
 
Hmm....does that black sponge over the intake valve help prevent fish from being sucked up into the valve? I lost a couple of fish that way, got too close.

Thank you all for the advice, I greatly appriciate it!
 
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