Water changes: Do i still need to change the water if paremeters are 0?

When Caulerpa is maintained properly it spreads vegetatively (asexually) by sending out runners that develop new fronds and rhizoids. However, under certain conditions it will reproduce sexually. From the perspective of a marine fishkeeper, this is undesirable, because after reproducing all the algae dies back simultaneously, releasing all their nitrogen and phosphate back into the water column as they decay, ruining water quality. Particulate matter that is released as the algae decays reduces water clarity, turning the water milky white and clogging up mechanical filtration media.

I'm not sure exactly what causes this, but leaving lights on 24/7 and proper trimming of the plant reduces the chances significantly.

Chaeto does not have this risk.

 

to the original question.

water changes serve 2 purposes.

1. reduce nasties (like nitratres)
2. replenish elements

If your nasties are fine (i.e. steady and low nitrates/phosphates, etc.) then 1 doesn't apply.

If your main elements (ca, mg) are consistent and fine (either due to low coral load or to regular dosing) then 2 doesn't apply. You are left with no reason to do a WC.

There is some truth to trace elements but there is NOTHING saying these are used up by the tank every week. So occassional WC is important, but weekly is way over kill.

My tank has been up for over 3 years and I auto dose and my params are rock solid. I do 3-4 WC a year and that's just for trace elements that I can't measure.