I am having a concrete roof-top splash pool built in Mexico; under 1500 gallons. No special jets, blowers, waterfalls, or spa-like features, and would like to keep it as simple and energy efficient as possible. Any suggestions for equipment? This part of Mexico (Yucatan) has a ton of roof-top pools (small and large - built in concrete), so I'm fairly confident there are capable builders, but any suggestions on construction techniques such as membrane material would be welcomed. Thanks in advance - Peter