Watt's Per Gallon (Wpg)

[carpking]

So then guys how do i work out my WPG is it simply divide my lights by water volume

i have roughly 40 gallons i think (180L) and i have x2 14watt T8 tube

so is it 40/28? so im 1.4 watts per gallon correct?

Where should i be at for a beginner trying to grow something green.

Thanks in advance

 

[DrRob]

The watts per gallon rule was calculated for T12's, kinda works for T8's assuming the tank isn't too deep and is otherwise pretty useless.
 
So, knowing that you have T8's, and assuming that your tank isn't too deep, then no, it's divide watts by the number of gallons in the tank, so you're at 28/40, which is 0.7

 

[carpking]

Thanks for clearing that up for me so 0.7 that's low so to improve this i simply buy a higher watt bulb i think i can get a 22watt in T8?

 

[DrRob]

Depends on the ballast, and of course, the length of the tank.

 

[carpking]

ok just checked my ballest 22watts seems to be ok on there so thats good my tank is roughly 90cm wide facing it

 

[daizeUK]

WPG is referring to US gallons I think, nearly every time you see gallons it means US gallons not UK so your tank is actually 47.5 gallons.
 
Your watts depends on how the lights are arranged.  14 watt T8's are only 15 inches long which seems very short for a 90cm tank.  If the tubes are aligned end-to-end (i.e. one at each side of the tank) then you've only got 14 watts over the whole tank.  So that's 14/47.5 = 0.3 WPG
 
I've never a tank with lighting this low, which tank have you got? 

 

[carpking]

Hi

The tank i s from Maiden Head Aquatics its the ones the sell that are set in the oak stand with the oak lid.

The tubes are set on each side of the tank but the tubes are nearly as long as the tank.

 

[levahe]

For a beginner to plants I recommend lower strength lighting. Higher intensity lighting will cause algae and will cause plants to be unhealthy unless accompanied by pressurised co2 and lots of fertilisers.