Question: 

 

What size UV do i need to kill whitespot?

 

Answer: 
 
The suggested radiation intensity to combat Whitespot is 72,000 microwatt’s/sec/sq.cm
 
To get this radiation intensity you would need to run the flow rates below through our UV units
 
10w - 230 l/h
20w - 460 l/h
39w - 920 l/h
80w - 1835 l/h
 

In a reef tank you want to pass the volume of the aquarium throught the UV 1-2 times an hour and a fish only system 2-4 times an hour. So for example a 39w UV would be suitable for combating whitespot in a reef tank of 460 litres - 920 litres.

 
Be mindful that pump manufacturers specify the max flow of their pumps without any head or pipe restrictions so a 1000l/hr pump for instance may only produce 600 l/hr when plumbed into the U.V
 
You are best to flow water through the unit from a pump into a bucket and time/calculate the actual flow through the unit for an accurate flow rate.