Originally Posted by AztlanLC
When building a bog filter 5' x 5' in this case and 30" depth, what would be on ideal flow rate for it, the pond is 1200 gallons and currently have a 3000gph pump
If this constructed wetlands filter is to be used primarily as a phyto-filter a.k.a. 'Veggie filter', ideally you want a low flow rate to allow for more Resident Time (RT) for the water. This will allow for maximum uptake of nutrients by the plants. To function at maximum efficiency, these structures should be constructed as an adjunct to the main pond body and not used as the prime source of flow for a waterfall or as the prime source for bio-conversion. Their primary goal is to 'Polish' the water.
I would strive for a flow rate between 500 - 1000 gph. In my installations, the wetlands has its own dedicated pump.