I think we may have fleas in our sandbox. We've seen several red bumps, look like bites, on my daughter after playing in the sandbox. A flea was found on one of the dogs after he lay in the sandbox while my kids were playing. (In ten years my dogs have never had a flea!) The sand box was covered until recently. I've heard cats can be a problem but we've never seen a cat, cat prints, or cat feces in the box. Anyway we were planning on removing all the sand and refilling the box but were hoping there was a non-toxic, natural way to get rid of fleas - assuming we even have them. The box is approx. 6ft x 6 ft and 1.5ft deep - made of cedar. Thanks.