Thank you for writing to me. I hope that you and your family are well. We ship to Mexico every week. There is no duty due to NAFTA. for that size pool you can use the Heat Siphon SX 3.25 with 80,000 BTU's if you use a blanket at night in the cool weather. If you don't use a blanket then use the SX 5.0 with 109,000 BTU's.
Scoll and piston compressors have the same reliability. Scrolls are usually a little more efficient and some people think they are quieter because they vibrate less. If you have many power interruptions where you live then get the scroll as it is better suited to the power coming on and off. Heat siphon travels very well and has a great parts warranty, so it is usually my first choice for Mexico.
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