water changes

[scoylesays]

I have a 20 gallon tank which actually amounts to around 17 gallons of water with the decorations. when I do a partial water change say 3 gallons should i only add enough seachem prime for the 3 gallons or for the full amount of water 17 gallons. Thanks.

 

[HN1]

If you are adding the water via bucket, then just dose for the amount of water you add back into the tank. If filling with a python, dose for tank volume.

 

[scoylesays]

ok thanks!