Please choose the correct ending to complete the given sentence: Pets and Animals: [header] How to clean a goldfish tank [title] Every week you will need to change about 25% (perhaps more depending on your water readings/types of fish you have) of the water in your tank. [substeps] How much and how often depends on the weekly test results and isn't covered in this article. This article is to give new keepers a guide on how to perform a water change in the most effective, least stressful manner.

Ending1: [title] Account for the cost of the water you use in your tank. [step] This can vary by aquarium, community and industry. Ending2: Performing this should be avoided because newer tanks usually need only do it once a week. [title] Move the fish into a larger tank. Ending3: Tank keepers can also use this guide if they are normally adept at building a firm tank. This can definitely be saved for when you are just starting out. Ending4: Less stressful for both the fish and the keeper that is. [title] Make sure you have some basic equipment.

Answer format: ending1/ending2/ending3/ending4