# PAR Readings



## TropTrea (Jan 10, 2014)

Par readings while not 100% accurate for the amount of good light given to plants are a much better comparison than using Lumns as well as Watts per gallon. This is especialy true now that LED's are beincoming more common and the quality range of LED's can vary from less to 80 lumns per watt to almost 200 lumns per watt.

We see recommendations for low-medium and high lighting for plants in the terms of watts per gallon. But with LED's as opposed to florescent lighting if we continue to look at it in that way we could actually have a range of 3X as much light light as another with another tank using the same wattage per gallon only a different type of lighting or brand especially with LED's now in the picture.

While I do believe PAR is not an answer to all I think it is a much better guide than Watts er Gallon. So for the people on here with excess to a par meter it would be nice to set up some base guide numbers. What are the PAR meter reading at the substrate in your tank? And do you consider it a low-medium- or high a high light level.


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## TropTrea (Jan 10, 2014)

For a starter I have two tanks that were converted from Salt water to fresh water with LED's on them. Both are 40 breeder tanks and the PAR readings are 118 at the substrate level. The LED I'm running on them are 6 Neutral White LED's running a 2 Watts each, and 24 Royal Blue LED's running at 2 Watts each for a total of 60 of LED lighting. I would classify these thanks as High lighting. But I realize there should be more red in the spectrum.


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## Michael (Jul 20, 2010)

When our club bought a PAR meter in 2011, we started a similar thread http://www.aquaticplantcentral.com/...tic-plant-club/80982-par-data-collection.html Not everyone has been as diligent about reporting results as we would like, but it is a start.


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## PhilipS (Jan 14, 2014)

Good topic.

I borrow a friends DIY PAR meter to measure the light at the plants.

Very good tutorial on utube search for "Understanding PAR & PUR & LUX"


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## Newt (Apr 1, 2004)

PUR is the only really meaningful one when talking about plant photosynthesis. PAR still encompasses green light but is better than lumens/lux, and wpg.


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## crazy4fids (Dec 17, 2014)

I'd love to get my hands on a PAR meter! I have an Aquatic Life LED EDGE lighting system. When I first got it and had both the lights on, I thought it was blinding!
So with my newly planted tank, I'm not sure which light (s) I should be runnung and for how long?


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## PhilipS (Jan 14, 2014)

$15 current brand dimmer switch should help keep it dim. Run the lights when you get to enjoy the tank.

I start with 4-6 hours daily for a few weeks. Then slowly lengthen to 7. Too much algae? Shorten the day.

Listen, the plants will tell you.


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## TropTrea (Jan 10, 2014)

Newt said:


> PUR is the only really meaningful one when talking about plant photosynthesis. PAR still encompasses green light but is better than lumens/lux, and wpg.


Yes that is true however how many people have access to a PUR meter? And as seeing from data I'm selecting from various sources WPG is almost useless when compared to PAR.

I'm gathering inf from several sources and presently I have about 50 sample readings. I'm doing some interpulation into the reading to establish a range in watts per gallons. From the data I have so far I did some adjustments on how many Watts it would require to obtain 50 PAR at the substrate of the various tanks that were reported. The first split I did was with reported light source.

For LED's I got a range of 0.65 watts per gallon to 1.125 watts per gallon. For T-5 Bulbs the rang was 1 to 3 Watts per gallon, and for compact florescent it was 2 to 7 Watts per gallon. I do not have enough entries for standard florescent bulbs or Metal Hides. From the data I'm getting I'm throwing out the extreme value on each end of the scale for that type of bulb and only using if I have 3 or more data points remaining with that type of a bulb.

Some interesting think I'm noting is the groups when sorted also seem to correlate with the height of the tanks as well. It seems like someone with a 20 flat tanks 36" X 18" X 8" can get away with considerably less watts per gallon than someone running a 20 Extra Tall Tank 20" X 10" X 22".

But I'd love to get more data point. So please if have access to a PAR meter give me more values.

Total Gallons
Type of Lighting
Total Wattage
Distance from substrate to lights
Par reading at Substrate.

Thanks


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