Yes, I'm the one with the PVC tubes weighing down our wedding cake steps. We had initially used sand to fill the tubes but switched to concrete a few seasons ago. We also drilled additional holes in the sides of the steps to facilitate circulation. Whenever I brush the pool I push water against the holes and watch it swirl up from behind the steps. As well, I put the fill hose behind the steps when I refill, to displace the water in that space. We've never had algae under the steps.