Ideal Flow Rate In Pond Filter

WATER FLOW RATE POND FILTER -- Flow rates are important for a few reasons. Firstly, it would be normal advice to filter the complete capacity of a pond around every 2 hours. This is the specification of the pump you are looking for. You will need a pump of around that flow rate after losses due to bends etc. Why is this important? It is simple and has two basic answers. Firstly the flow rate has a major effect on the biological capacity of the filter. These filters work using naturally grown nitrifying bacteria which help change noxious ammonia (liquid fish waste) into noxious nitrites, and finally into harmless nitrates .


 Calculating ideal flow rates and filter retention times for koi pond filtration systems can sometimes be contradictory and for the average koi keeper with modest stocking levels and a reasonable filter there shouldn't be a problem. But there are a lot of over-stocked ponds with pretty poor filtration systems - find out why.

When it comes to filter sizing, life can get complex. As I've said, if we only wanted simple nitrification, it is probable that filter sizes would be small. Pond water turnover rates and filter flow through rates become critical factors when using a filter. If the turnover and flow through rates are too low, the pond’s healthy environment will rapidly degrade.

 To calculate ideal flow rate and retentions time in your koi pond filtration,lets do this steps:

• Determine your water feature’s volume by calculating the area of the pond then multiplying the area by 7.5 to get the volume in gallons: Rectangle: Length x Width=Area Oval: Measure from the pond centre to the most distant edge (A), then measure from the centre to the nearest edge (B). Multiply A x B = C then C x 3.14 = Area Circle: Measure from the centre to the edge to get the radius (r). Multiply r x r x 3.14 = Area Abstract and irregular: Multiply the maximum length by the maximum width = Area Oblong: Break the space into two half-circles and one square. Calculate the area of the square using L x W and the area of the two half-circles by joining them and using r x r x 3.14. Add the two results together for the total area of the oblong. 
•  Determine your water feature’s turnover rate by reviewing the gallons per hour (gph) rate of your pump with the filter attached compared to the total volume of your water feature, for example, a 1,000 gallon water feature needs a pump that can cycle through at least 500 gph to ensure the total volume is ‘turned over’ once every two hours, 12 times per 24 hours. 
• Determine the filter flow through rate by dividing the concentration of ammonia and nitrate by the optimum level for the water feature to get the ideal flow through rate to achieve that level; for example, the optimum level of ammonia and nitrate for Koi ponds is 0.0025 milligrams per litre (mg/L). Assume a production of ammonia and nitrate of 817 mg/day, you can find the ideal flow through rate with this equation: 817 mg/day divided by 0.0025 mg/L = 326,800 L/day or, 86,275 gallons/day = 3,535 gal/hr or about 60 gal/min
 

 

Source: 

http://www.headsquared.co.uk/ponds/articles/feed_rates_and_filters.php http://www.ehow.co.uk/how_5969003_measure-turnover-filter-flow-rates.html http://www.fishdoc.co.uk/filtration/koi5flow.htm