Level 1; What is the correct response. Water change volume.?

Question

I am doing a water change in a 100 gal. tank. Using a canister filter to clean the gravel. How much water do I remove and replace.

Answer 1

25 gallons per week.

Answer 2

The answer has too many variables that is based on what your water quality is like at the time of water change.  If the water quality shows little to no nitrates, then a 10 percent water change a month is sufficient.  If the nitrates are higher, then of course a larger amount of water needs to be changed out more often to dilute the nitrates .  Simply doing a water change will not dilute your nitrates by the same amount.  Meaning if your nitrates were lets say at 100 mg/l , changing 25% will not drop it down 25%.  Numerous water changes will need to be made to simply dilute the nitrates enough to be within acceptible range.  Also, if you have a lot of debris that hits your substrate such as plant matter, algae, fecal matter, this all will have to be removed before it breaks down and becomes a part of your nitrate issue.

Answer 3

20 to 25% depending on the stocking level of your tank.  An overstocked tank requires more maintenance.

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