Water change percentages and how often...

Plants will naturally also be of massive benifit to your water quality!

 

Not everyone is a chemist, and 50% weekly will help support a densely stocked tank like his. Especially if he feeds a lot. 50% once every second week would do more than 25% weekly. For a 3ft tank 50% will be easy, so why not weekly? Now the load may not be so great. But it'll increase over time.

This definitely helps, having enough nitrification surface to process waste, but often nitrate is left behind which only plants, water changes or dedicated anaerobic filter will deal with. Nothing beats a water change

 

I am sorry, but may I please correct you; aerobic bacteria generally easily take care of the amonia and nitrates. Plants naturally absorb nitrates I agree, however there are strains of anaerobic bacteria which anhilate nitrates! They tend to be somewhat fragile so it is not good to be overzealous when occasionally flushing your bio-filter. You can purchase these strains and are included in Seachem's Stability

 

Oops wrong quote and ok I see you're aware of the anaerobic, sorry @Hendre

 

And I first meant, amonia and nitrites! Both poisonous to fish!

 

Interestingly nitrates are not very poisonous, just long term exposure causes problems. Different species have different nitrate tolerances. Discus for instance; have a low nitrate tolerance. Generally speaking, nitrate levels are the biggest and all important hurdle for even the most advanced of us have to overcome on a regular basis.

 

100%

Tank size filter/bio filter size, and fish type and stocking levels is what will determine your water change needs
I also believe what you feed plays a role

We also do between 50 and 80% water changes weekly
My tank water goes straight to my vegetable garden which feeds 4 households and my staff so... it doesnt go to waste

 

@Reedfish Well we are all entitled to our own opinions! There are too many variables to make just one answer to this question.

 

This plays the biggest role actually. The more you feed, the faster you destroy your water.

There is one answer to this question and I already gave it. You are right, there are to many variables so why not work with one only, nitrate.
So the correct and one answer is, test your nitrates to see how much pollution your tank is producing and work out your water %. Simple as that.

 

I do a 50% change every second weekend. Seems to work well for me and the fish.