Wpg

[Nick16]

hi, when calculating WPG is it US gallons or 'english' gallons?

 

[three-fingers]

US gallons rather than imperial gallons .

 

[OldMan47]

It really doesn't matter. The calculations that we use are not accurate enough to worry about how big the gallon is. They are within less than 20% of each other but a plant that people suggest 2WPG will grow fine at 1.5 or 2.5. The typical WPG recommendations were created during a time when lights were T-12 type over a 55 gallon tank or one about that size and an average at best reflector. Where we live now is with T-8 or smaller diameter bulbs, good reflectors and a huge variety of tank sizes. These all affect the light going into a tank more than the gallon size does.