Why Do I have to do Low % Water Changes???

[munoza]

I am just curious, what is the main purpose of doing water changes? and why do they have to be 25% 30% 40%? Please if someones knows technical answers I would appreciate the information, just so I have a complete understanding. I would like to learn as much as possible.

[edward198]

Ive always thought you do low changes like 10,20% changes so you dont remove too much of the 'good' bacteria in the tank and to reduce the stress of the fish.. someone correct me if im a million miles off!

[josh7]

Originally Posted by munoza

I am just curious, what is the main purpose of doing water changes? and why do they have to be 25% 30% 40%? Please if someones knows technical answers I would appreciate the information, just so I have a complete understanding. I would like to learn as much as possible.

You do larger like 50% water change to get fresh water with no nitrates in it so your fish have a healthy environment. Also it is to remove fish pee and poop from the water to do they don't have to live in it. That's basically the purpose of water changes.

Also the small water changes like 10% are kind of pointless just do 1 big one a week.

[Thumper828]

Plus the buffers that keep your pH stable deteriorate, trace minerals are also lost. Best thing to do is a 50% change 1 a week.

[Rivercats]

There are many different types of toxins that build up in a tank. By doing a large weekly WC you are ensuring that the water will have low levels of toxins and if your tap water is hard with a higher kh you are also replacing buffers back into the tank water which is what keeps your ph stable. Large WC's when done properly do not stress fish. In fact I actually add water back 1-3 degrees cooler than the tank water which often triggers many of my fish to spawn either that day or the next morning. My fish are always very active after a big WC.

[Masha]

...just to add, the beneficial bacteria are not in the water. As soon as they find a food source, they glue themselves onto a surface near the food source. That means they cover every surface in the tank, but especially the filter media. Water changes dont remove BB

[Scottyhorse]

Originally Posted by edward198

Ive always thought you do low changes like 10,20% changes so you dont remove too much of the 'good' bacteria in the tank and to reduce the stress of the fish.. someone correct me if im a million miles off!

There is almost no bacteria in the water column so large water changes are fine. Discus keepers do 75% and more water changes daily when growing out juvies.

[jlk]

Originally Posted by Scottyhorse

There is almost no bacteria in the water column so large water changes are fine. Discus keepers do 75% and more water changes daily when growing out juvies.

Serious goldfish enthusiasts and breeders follow the same type of water change schedule (75-100% every other to daily).

It's worth noting though that some people are not able to do big water changes (50%+) due to their tap water quality. Just something to keep in mind .

[Scottyhorse]

Originally Posted by jlk

Serious goldfish enthusiasts and breeders follow the same type of water change schedule (75-100% every other to daily).

It's worth noting though that some people are not able to do big water changes (50%+) due to their tap water quality. Just something to keep in mind .

True about the tap water. Last winter my tap nitrates tested as high as my test kit would go. Could have been bad tests, but who knows. Hopefully it doesn't happen again and I don't loose any fish if it does?

[Fresh2o]

Originally Posted by Scottyhorse

True about the tap water. Last winter my tap nitrates tested as high as my test kit would go. Could have been bad tests, but who knows. Hopefully it doesn't happen again and I don't loose any fish if it does?

I remember your high nitrate dilemma.

Last year my tap was 1.0/0/5 for Amm/trites/trates so I kept the WCs to 30-40%. This year they tested 0/0/0. The WCs are more like 40-50% now.