omnitheforsaken

I keep reading about different lighting levels for plants. A "low light" plant, and "high light" plant, etc. But I never see these terms clearly defined. Can some one tell me the WPG range for each level or some other clear way to define them if that doesn't work?
Thanks

pepetj

You will find, with plants, some mixed information as it happens with some fish data.

However it goes something like this: below 2WPG is considered low light. Between 2-3WPG is considered medium; at or above 4WPG is considered High.

I suggest you look for info on "level of care" of plants and stick with the easy to care ones as you get more experience keeping plants.

The subject of lighting is quite complex, one that I am trying to understand. In the end it is photosynthesis what we are talking about.

Temperature of the water, dissolved CO2 levels and ligthing levels, all three need to co-vary within certain range to make photosynthesis possible. On top of that plants need micro and macro nutrients from both the substrate and the water column.

I began keeping plants with the lo-tech approach: Using the lights that came with the tank, not injecting CO2, and using inert substrate.

I was capable of keeping Anubias barteri, Egeria densa, and Sagitaria species. I failed with most other plants: Swords, Water Sprite, Hornwort, Vallisnera...

The term Watts Per Gallon is a quite deceptive rule of thumb (almost like -IMO worst than- the 1" of adult size fish per gallon). Watts is the energy the lamp uses when is on (without a dimer of course). In terms of light output, watts from an incandescent bulb (some 5 and 10 gal kits still come with those) are not comparable to watts from a straight fluorescent T-12 lamps (the old standard fluorescent, now-a-days we see more standard aquarium kits coming with T-8 lamps).

Indeed incandescent is considered the same as a 25% Watts rated fluorescent, in optimal conditions. Have you seen the marketing of compact fluorescents showing a 25W as equivalent to 100W lightbulb? That's the concept more or less.

To talk in terms of WPG can be misleading but still useful if you check other variables. As a rule of thumb, for tanks that are not tall (say 20 or 21 inches height the most), fluorescent T-8 lamps rated at 6,400 or 6,500 or 6,700K (varies with manufacturer) provide a good balance in terms of natural looking tank and useful light for photosynthesis.

Check the electronic ballast that came with your unit to see if you can upgrade your lamp a bit (I could move from 15W to 17W, and from 17 to 20W in some tanks. Doesn't seem much? it's like a 10% increase! ...until I checked the unit that measured the light output... Here I met with candle units, lumens, lux; and then I met the output of the type of light that is useful for photosynthesis and met terms as PAR, PUR... I'm still figuring things out.

Hope this is not too confusing

Pepe
Santo Domingo

omnitheforsaken

Thanks pepetj and not too confusing.

I'm focusing on my Java Moss and Java Fern right now. I have a 29 gal tank, 40 watts of lighting total w/ combined K of 7000, 1950 Lumen, 215 Lux using 2 T-8's (Hagen's Flora-Glo and Sun-Glo). I often read they should do fine in Low Lighting conditions but never knew what constituted Low Light. I more so needed to know so that I could know my limits as far as what plants were even an option to me with my current lighting and so that when the time comes I can plan my upgrade properly.

You lost me with the PAR and PUR, first time I've seen these terms but you've given me enough info to start with. I can research these terms I'm sure.

Thanks again