2 WPG lighting. High, Low or Moderate?

A

andyjh

AC Members
Feb 18, 2009
574
3
18
Massachusetts
I've noticed that the fish stores often tag their plant's lighting requirements as either low, moderate or high. I'm never sure what category 2 WPG falls under. I'm guessing "moderate", but would love to hear your thoughts. (and any plant recommendations for someone like myself who's just getting into the idea of a planted FW tank.)
Andy
 
IMO, considering the different types of aquarium lighting available, watts per gallon doesn't tell you a whole lot. For example, 2 wpg of NO flourescent light is much different than 2 wpg PC light, which is much different from 2 wpg HO T5 light. No bulbs put out the least light out of these, while HO t5 bulbs put out the most light out of these. However, the amount of light you get out of T5 bulbs is largely dependent on the number and quality of reflectors you have in your light fixture. Single reflectors give you the maximum light output from T5 bulbs.
 
The size and dimensions of the tank play a role. A tall 37 gallon tank with 2 watts per gallon of lighting may be able to support only low light plants, especially if no CO2 is added. A shallow tank with the same wattage and with CO2 would be capable of growing most moderate light plants I should think.
My 40 gallon has 2.1 watts and no CO2. I grow low and some moderate light plants.
 
2 wpg on a 5 gallon tank is so low to be almost no light while 2 wpg on a 500 gallon tank is crazy high light. The amount of light isn't linear but, in the typical size range most people's tanks are, 2 wpg is somewhere in the middle depending on the tank.
 
Great points. What I'm getting from this is that the WPG measuring standard has some serious flaws! Any plant suggestions for my "flawed" 2 WPG in my 55?
 
You can grow just about anything in your lighting configuration. You have 110 watts of light. That's plenty.

The WPG is a rule of thumb and obviously doesn't apply at the low and high ends of the scale. A good way to look at what is "typical wattage" is to look at some of the the lighting hoods that are offered for your tank size. I'm not talking about the one that comes with the tank. I use a hood that has 260 watts of light on a 110 gallon. That's a little over the 2 WPG "guideline" and that works out great! I don't have any high light plants, just moderate to low and have excellent results.

There are manyoptions out there. More light means more plant growth and algae growth. This might also drive you to having to use CO2, fertilizer, etc if you opt for high light. Just something to think about.

Best wishes!
 
With similar lighting and no CO2 I have great success with crypts, jungle val, anubias, java fern, and assorted bulb plants. I have good success with ludwigia repens, only fair luck with hygros.
 
2 watts per gallon grew nothing in my 55, except low light plants and not that great, 2 watts per gallon in my 29 and I can grow a wholelot more and do.
 
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