The problem is these little guys are really messy. They go in and out of the water all the time so they are constantly dragging the substrate into the water. As a result the water is hard to keep clean. Its best to use some cover over the soil such as leaf litter or sheet moss. The problem is the sheetmoss tends to die off when it gets too wet. You can't use sphagnum moss because the crickets hide in it and the frogs will accidentally injest it while eating. You can use larger smooth riverbed stones around the waters edge to help keep some of the soil out of the water. Bottom line is the children go in and out of the pool all the time and its going to be hard to keep the water clean. Get a good filter. Also use plants such as Pothos that don't mind getting drenched and climbed on.