I use pool filter sand without any issues. I've never lost any pumps or other equipment to sand issues. It's easy to clean and heavy enough to not float around when disturbed. I tried play sand before but I found it to be too light. It floated around too much when disturbed. To me pool filter sand is the better option of the two. I also have gravel in one tank that I will be switching to sand soon. Food and waste are easily trapped in the spaces between the gravel. Unlike sand, my gravel bottom tanks take longer to clean because I have to make sure that everything is picked up from the spaces in the gravel. With sand, the waste stays on top where it is easily taken up.