My tank is crashing

[JohnK]

^ second that. It might not seem like a big deal, but any impurities in your top off water will only accumulate so that a tiny level of any contaminant in the water will gradually build up in your tank water until it's not so tiny a level anymore...

 

[P-Nut]

^ second that. It might not seem like a big deal, but any impurities in your top off water will only accumulate so that a tiny level of any contaminant in the water will gradually build up in your tank water until it's not so tiny a level anymore...

Water changes.

 

[mchartier]

Water changes.

With the same water that contains the impurity so it really is not removing it.

 

[jselzler1]

With the same water that contains the impurity so it really is not removing it.

Water changes keep it diluted to similar ppm as source. Topping off without water changes does allow the concentration to increase.