Bests & Worsts Reviews from Amazon

Based on documentation the heater is intended to "maintain temperature of warm water" First use hinted that it wasn't doing the job, so I ran some tests with a digital thermometer. Hot tap water with the unit not plugged in lost 10-11 degrees in 10 minutes. Same test with the heat/bubbles ON showed a drop of 28 degrees in 10 minutes. Another test with heat/bubbles plus waterfall shoed a drop of 31 degrees in 10 minutes. Conclusion: the heater is too feeble to keep up with heat loss from room air being mixed with the water (bubbles or bubbles plus waterfall). We returned for a refund.