we restored a cottage- all new plumbing and plumbed shower, sinks, toilet into existing cesspool. Maybe 3-400 gal tops. Used mostly weekends until this summer when son moved in, and we use on weekends- 4 adults, multiple showers. Now can't flush- up to 2 horurs after shower. Had the tank pumped, and installed flow regulators & plan to put in an outdoor shower but afraid problem will still be there. Will this product help?