I've done small % water changes, but I don't even know if I'm doing it correctly. I usually use a 2 cup measuring cup and remove up to 1/4 of the water, and pour the new water in over the filter. It seems to work fine, but how do I change 40%? Won't that make the tank shallow and messy? Please correct me if I'm doing this wrong.

I have a bucket that holds approx. 5gal, which is half of my tank (10gal) when i want to do a big water change, i fill the bucket up to where i know it needs to be (thats just pracise i suppose) and let it sit out for the day/night. the next day i add water conditioner. then use another bucket (empty) and i have a gravel vac so i syphon out the water from the tank and into the empty bucket. when i've taken out enough/finished vacin', i set the bucket full of new/clean water on top of my tank (cuz it has to be higher than the tank to siphon) and i siphon the new water into the tank
sounds confusing probably, and i'm not good at explaining, but thats how i do it

When I do a water change I use the following equipment:
*2 buckets, one (it should have never been in contact with any soaps or detergents - possibly new?) for moving clean water to the aquarium or you could use clean jugs, the other for transporting dirty water from the tank to empty it.
*a gravel vacum/siphon to take all the debris from the bottom. Taking the fish waste, un-eaten food, and plant decay if you have live plants, out of the water that the filter could not would decrease the chace of high ammonia and nitrites.
*you could also use water conditioner - to make sure the water you are putting in your tank is safe from clorine.

I fill up the clean water bucket with water from the tap and cover it with a towel to make sure no dust gets in. If you are planning to take more water out of your tank than the water in the bucket, get another bucket to fill up too. Condition it. Wait at least 24 hours before chaging the water in your aquarium.
Now what I do is tank the hood off the tank and light and disconnect the filter( and heater if you have one). Then I activate the siphon and move it around the bottom of the tank, the siphon will take the devbris out and water at the same time. When you have done 30 -40% water change, take the siphon out. Rinse a FEW (if your plants are plastic or silk) of your plants, rubbing them. Then place them back where you want them, and fill up your tank to the correct level with the water you have pre-cinditioned and been sitting for the last 24 hours or more. Then clean out your filter. Place the hood and light back. Plug everything back in and there you go...

I use a similar method to the previous poster. I use a gravel vacuum to clean the bottom of the tank and syphon out the required amount of water. I generally change between 30 - 40% per week. If the tanks are bare bottom, I just use a syphon hose.

To fill the tank, I use 2 and 2 1/2 gallon watering cans. I condition my water with Prime. Other than the small betta tanks which require 100% water changes, I don't worry if the water is directly out of the taps. I just match up the temperature and add the water conditioner, then pour the water from the watering cans into the tank. I try to direct the flow of water to the side of the tank, against the glass, to keep from disturbing the bottom, and also to keep from creating too much turbulence for the fish

If you add new water this way, make absolutely sure that there is no chlorine or other toxin in the water, and that the pH of the new water is the same as the pH of the tank. If you are not careful, you can kill your beneficial bacteria every time you do a water change.

I pretty much do it the same way as the others have posted. I'd just like to add that I clean my filter sponges once every couple of weeks by squeezing them in the bucket of old tank water: I don't rinse them under the faucet or replace them brand new as often as the box says that you need to. When they do need replacing, I make sure to save a chunk of the old media to seed the new sponge.

Are the gravel vaccum expensive? I'd like to get one. It sounds like it would help alot.

Oh, and I always let the water sit overnight, but I don't have a conditioner. I saw one at nooppee but I didn't know I needed it. I think it was AquaGuard.

No they are generally pretty cheap. Look for them at nnnnnn. Don't get the ones that say they remove waste without removing water, you WANT to remove water and waste at the same time.

I think letting the water sit overnight or for a few days is good enough, but if you are on city water I wouldn't put it directly from the tap into your tank. Keep up with letting it sit or you can get some Wardley's Chlor-Out or Amquel to treat it before putting it in if you can't let it sit.

If you use a chlorine remover/tap water conditioner, how long does it take to remove the chlorine? Is it instantaneous? I put an airstone inside the water container and let it sit for 5 minutes, is that long enough? I'd hate to think I was killing my bacteria off all this time.

The reason I don't let water sit out is because I have over 200 gallons of water that I am maintaining. In order to change 30 - 40% of the water per week, I would have to have 60 to 80 gallons of water sitting around the house


I use Prime as a water conditioner, and it is excellent. Also, it works pretty much instantaneously.