Please choose the correct ending to complete the given sentence: Home and Garden: [header] How to make a water purifier [title] Acquire your parts. [step] You will need two 5 gallon (18. 9 l) food-grade plastic buckets with lids, and a food grade spigot. You will also need a pair of water filtration elements.

Ending1: [substeps] You may need a tank head unit from a local hardware store. [title] Select a machine or inverter of the same size to use. Ending2: These will be the most expensive part of the project. [substeps] Make sure that your filter elements are nsf certified. Ending3: If you submerge up to 110 gallons (20. 92 l), you will need enough garden gravel in each bucket to provide water to the garden. Ending4: [substeps] You should also make sure to use a good filter. A filter connects the water purifier to a central water source, and also heats up water the same way as a water recycling system does.

Answer format: ending1/ending2/ending3/ending4