We had decided to put in a rock garden and pond and stopped at Oak Park for ideas. The girl working there was so very knowledgeable, we ended up buying everything we needed for the pond. She was very honest in her recommmendations and we bought exactly what we needed for a great looking garden and pond. They will retest your water whenever you want which is another great asset. When we couldn't get the water right, we took in a test sample and they told us exactly what to do to make it perfect. Great company!