You could ditch some of the rocks so that the water flow reaches the other corners of the tank. I doubt your frogs will drown, just make sure there are several things in the water for them to climb out on if they do fall in. I have a full water bottom for my red eyed tree frog, he scoots his butt down to the water at night and sticks his whole lower half in the water, then climbs back up. Best part is no foggers needed. I spray inside the cage usually once a day and the humidity is never an issue. I cover half the top with saranwrap and the other half has the light. There are live plants in ceramic pots, which the frog can climb on if it ever fell in, as well has a fake fern and a fake lily pad. And I cup feed him to avoid dead crickets in the water.