I heard you can do a 100% water change in your Aquarium...?

Question

Is this true? I hear 25 to 50% all the time, but I have wayyy tooo muuuuch food left over after cyphering out 50% of it.

Answer 1

No you will destroy the bacteria that break down waste. Simple solution, don't over feed your fish.

Answer 2

100 % water changes are possible, but you need to have aged water. Water from the tap is high in CO2 and the PH will fluctuate as the CO2 is released, which can stress fish if it happens in the tank. Tap water in also usually full of chlorine, which is highly toxic to fish. Chlorine will leave the water as a gas, but it takes approx. 24 hours for this to happen, and you need some type of aeration (bubbles) to aid the offgassing process. A dechlorinater (like stress coat or amquel) is a better and safer bet if you aren't familier with the way chlorine and water interact.

Another factor is temperature. Fish can get extremely stressed if the temp in the new water is even just a few degrees different--their metabolism is dependant on temp, so it can really affect them if it isn't just right.

I do 80-90% water changes because I breed discus, and they need very clean water. The water I use has aged in a big plastic tub for no less than 24 hours. It has been heated and aerated, and I double check the temp before I use it. I wouldn't recommend 100% water changes unless you have a complete understanding of water chemistry and a proper setup to "prep" the water first.

25% water changes are recommended to the average hobbyist because even substantial differences in water chemistry won't have much affect on the fish if it is only 25% of the total water.

To best solve your problem, I would recommend reducing the amount you feed. Your fish should be able to every little bit in about 2-3 minutes. Anything left over after 2-3 minutes is excessive and indicates the fish don't need as much as your're feeding. Less food per feeding and more frequent feedings (3-4 times per day) works best. I hope this helps!

Answer 3

No you cant do 100% if there are fish present in the tank because the chemical balance of the water will be too drastically changed and you will start the ammonia cycle all over again . If you have too much food left after 50% you are either not siphoning the gravel or feeding too much or you need a better filter.

Answer 4

What kind of fish do you have and how many?

I did a 100% water change on my betta's tank because I was absolutely desperate (had way too much food and chemicals). I was able to house my betta elsewhere for a few days while I got my aquarium running again. Used the same air stone and filter. I still have problems with ammonia...

Good Luck

Answer 5

You really should not change all of the water at once. It is stressful for the fish because they suddenly have to adjust to all new water and its new chemistry. It stresses the fish. It is only recommended in dire emergencies and never on a regular basis. Frankly, if there is tons of leftover food on the bottom of the tank you are overfeeding. A fish has a stomach roughly the size of its eye. Only feed what the fish will eat in about one minute 1-2 times per day. People tend to over do the feeding of fish. Fish always beg for food. Food is scarce in the wild so they have to constantly look for it in order to find enough. They do this in a fish tank, too, but since we are providing plenty of food it causes problems. More fish die from being overfed than underfed. Cut back on the feeding. Your fish will thank you for it!

Answer 6

Some of these replies are inaccurate. The beneficial bacteria don't live in the water column, and aren't lost during water changes (not in great numbers anyway). Bacteria that break down ammonia and nitrites live on the surfaces in your aquarium. Most are found within the filter media and the gravel. Changing large amonts of water will not affect the number of bacteria enough cause a disruption in the nitrogen cycle.

The reason you shouldn't change 100% of your water at once isn't related "beneficial bacteria". It is a because abrupt changes in water chemistry can stress fish and cause illness.

Answer 7

Doable but not recommended. Aside from the needs for a holding tank or container for your fish you will be most unhappy when your water goes cloudy from a bacteria bloom. Or your fish die because all the beenficial bacteria have been siphoned off leving them susceptible to the severe ammonia burn of what is, for all intents and purposes, a brand new uncycled tank.

Feed less (the poster with the quote on stomache size is spot on) and, if necessary and to help keep a check on yourself, invest in a couple of inexpensive cory catfish to manage the waste.

Answer 8

Unless you have a back-up aquarium that could house your fish, while doing the water change and waiting for it to go back to the right Ph, etc.....

Do not do a 100% water change. Instead, decrease the amount you are feeding, if there is excess food.

Answer 9

I typically and historically have done 100% water changes only with the smaller tank sizes, and even then only in unfiltered aquaria(not really practical for anything larger). Plus, there are some fish species that are sensitive to heavy water changes(example: Tanganyika cichlids). You can get special siphon tubes that have an attachable "wide end" tube that can actually vacuum clean the gravel. And, of course, try not to overfeed the fish.

Answer 10

If you have alot of food on the bottom of your tank try feeding less.There shouldn't be any food falling to the bottom of the tank when you feed.You should also use a gravel siphon if you aren't already.It isn't a good idea to change all your water.

Answer 11

No, unless it is an emergency you should never ever change all of the water. 25% is all you should be doing at a time. Wait 3 days and then do another 25%.

There are benificial bacteria in your aquarium water that your fish need (hence the importance of proper cycling).

Just start feeding less food from now on.

Ally