I help maintain an indoor pool for our HOA. We are getting a good amount of DE in the pool recently. The company that services the pool charges $175 for an annual inspection and cleaning of the DE filter. They were notified of the problem with DE getting into the pool and sent us an estimate for $420. $175 for filter cleaning seems reasonable. Would replacing grids increase the cost to $420.? And this is before they even know if any grids are damaged or how many need to be replaced. Just trying to get a sense if this seems to be fair pricing. Thanks for any input on this.