High light vs low light

[Johny]

Without having a meter to actually measure the amount of light at different points in your tank, how do you know if your in the high/medium/low range?

For example I have a 65 gal tank (36" wide 24" tall 19" deep) with a single finnex planted + 24/7. What range does that put me in?



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[Delapool]

I think this has been measured but don't have a link to it unfortunately.

 

[Caliban07]

Without having a meter to actually measure the amount of light at different points in your tank, how do you know if your in the high/medium/low range?

For example I have a 65 gal tank (36" wide 24" tall 19" deep) with a single finnex planted + 24/7. What range does that put me in?



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Without a meter you don't really know. Sometimes manufacturers lost their par values on the box but these could be measurements taken in air in the perfect environment. In reality, water and organics can absorb light and the intensity is drastically subdued at the substrate because of the inverse square law. The more intense the light the more photons will be present at a particular depth in your aquarium.

I don't even want to give an estimate because really you need a meter. Or someone like delapool who has access to tried and tested information but even then. No two tanks are the same and so PAR Would still only be an estimation.


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[Johny]

Delapool and caliban
Thank you for responding.
I originally assumed I was in the medium light range, but I'm finding that shorter plants (less than about 8" when planted) struggle, but the same type of plant, if a little taller when planted will grow very quickly. This leads me to believe that I am not getting much light at the bottom of the tank.

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[Caliban07]

Delapool and caliban
Thank you for responding.
I originally assumed I was in the medium light range, but I'm finding that shorter plants (less than about 8" when planted) struggle, but the same type of plant, if a little taller when planted will grow very quickly. This leads me to believe that I am not getting much light at the bottom of the tank.

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Light (mainly) and carbon dictates the rate of photosynthesis and thus growth so I plant that has much of its mass closer to the light and atmospheric carbon will naturally grow quicker.

If a plant is growing then it is receiving light levels above its light compensation point. If a plant is dying then it could be receiving light lower than its LCP and if it is neither dying nor growing it is probably at LPC. It is possible to have slow healthy growth just like it is possible to have fast unhealthy growth.

Is the smaller plant dying or just growing slowly?


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[Johny]

A little of both. Some have stayed (so far as I can tell) the same for a month. Others have melted away. I think the ones that melted away might have been a bit overshadowed by other plants.

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[Caliban07]

A little of both. Some have stayed (so far as I can tell) the same for a month. Others have melted away. I think the ones that melted away might have been a bit overshadowed by other plants.

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In that case you may be right. What kind of lighting do you have?


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[Johny]

Finnex planted plus 24/7

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[Johny]

We have been using it on the 24/7 setting.

I started a little bit of an experiment 2 days ago. I still use the 24/7 overnight to get moon and sunrise effect, but once the light starts going towards regular daylight I turn it to max and leave it at max until late evening. Its only been two days ( today the third) but I haven't seen any increase in algae so far.

I really don't want to buy a second light. They are nice, but expensive.

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