Reddit mentions of Mini Polario 4ML Low Voltage Water Pump, 600 to 1000 GPH

I have a 20 Long with a single Polario 4ml. It does an incredible job and single handedly replicates the ebb and flow of a natural reef environment by reversing it's flow every 15 seconds and varying the intensity. My corals noticeably increased in size and color once I added it into my tank. On top of being a really great pump, their customer service is outstanding. I can't speak highly enough of them so far. For a 30 gallon I would bump up to the 7ml model. For the price I really don't think you can get any better. Admittedly, there is a small whine at max power, but I keep my tank in my bedroom too and it never keeps me awake or prevents me from sleeping at all. I think a lot of reef people are just afraid to try them because there isn't much review on them, but do a little research on them, I don't think you would be disappointed and it's exactly what you're looking for.