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Discussion Starter · #1 ·
I have 2 lights on my 75. One light makes 71par at 18inches. If I reduce intensity to 50%, do I have 35par at 18inches? And with 2 lights, 3 inches apart, if they are both at 50%, will i have about 70par at 18inches?
 

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so sure, makes sense. But I don't think it's accurate. I think that holds up, cutting in half for the first 10 inches or foot. But at deeper depths I think PAR falls off faster. as far as the cross over from the two lights it won't be double either. so I'll address each seperately.

I don't know exact numbers but from looking at charts... I would expect the light to produce more like 28-32 PAR at 50% at 18 inches.

Also that is likely directly under, so even just three inches will likely bring the PAR down a little more, say another 5-10%? call it 5%.

So, again, a lot of aproximating, but I would guess to get true matched lighting with two lights vs one light at 100% you would want something closer to 60% on the pair.


Now, I am going to make an assumption, you have two Fluval 3.0. I have one, started her nice and bright on my 75 gallon, it's now down to the 30-60% range depending on what of the 5 settings you're talking about. This is just one 3.0 on a 75 gal. I backed this down because I started to notice a quick increase in algae, brought it down and haven't noticed any loss in plant growth and way less algae.
 

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Discussion Starter · #3 ·
so sure, makes sense. But I don't think it's accurate. I think that holds up, cutting in half for the first 10 inches or foot. But at deeper depths I think PAR falls off faster. as far as the cross over from the two lights it won't be double either. so I'll address each seperately.

I don't know exact numbers but from looking at charts... I would expect the light to produce more like 28-32 PAR at 50% at 18 inches.

Also that is likely directly under, so even just three inches will likely bring the PAR down a little more, say another 5-10%? call it 5%.

So, again, a lot of aproximating, but I would guess to get true matched lighting with two lights vs one light at 100% you would want something closer to 60% on the pair.


Now, I am going to make an assumption, you have two Fluval 3.0. I have one, started her nice and bright on my 75 gallon, it's now down to the 30-60% range depending on what of the 5 settings you're talking about. This is just one 3.0 on a 75 gal. I backed this down because I started to notice a quick increase in algae, brought it down and haven't noticed any loss in plant growth and way less algae.
They are both Fluval 3.0. Yeah, I keep getting green water followed by GDA and GSA. So I reduced to an 8 hour photoperiod. Here's my current settings. I think my most demanding plant is Ludwigia Ovalis and Repens.
 

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They are both Fluval 3.0. Yeah, I keep getting green water followed by GDA and GSA. So I reduced to an 8 hour photoperiod. Here's my current settings. I think my most demanding plant is Ludwigia Ovalis and Repens.
So again, I can't get mine but I have less light than that. unless that is literally just the red and the warm white. I use all 5 but with variances across the board. I took the Pro setting and adjusted that so there is a dip for an hour in the middle of mine. I also set up a longer moonlight period at the end for my personal viewing prefrences. I'll try to remember to get that on there when I get home.

But main point, I have one 3.0 on a 75, i forget what your tank is, with settings lower that this. Where as I'm guessing both your lights are set up the same or very similarly to each other.... Sounds like you're over doing it with the lights and that's where the algae is coming from.
 

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Discussion Starter · #5 ·
So again, I can't get mine but I have less light than that. unless that is literally just the red and the warm white. I use all 5 but with variances across the board. I took the Pro setting and adjusted that so there is a dip for an hour in the middle of mine. I also set up a longer moonlight period at the end for my personal viewing prefrences. I'll try to remember to get that on there when I get home.

But main point, I have one 3.0 on a 75, i forget what your tank is with settings lower that this, where as I'm guessing both your lights are set up the same or very similarly to each other.... Sounds like you're over doing it with the lights and that's where the algae is coming from.
Okay, I'll drop it even more. Yes both are mimicking each other. All the whites are the same and blue is only 4% at its highest. I'm interested in seeing your settings. Thank you!
 

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well, I guess I changed them at some point. this is what they currently are. snapped screenshot walking out the door this morning. Probably gonna play with them this weekend. I barely see them on work days. again, just one 3.0 on a 75. lights were adjusted for my preference and also lowered to this for algae purposes.

So I did change this again. I made changes and then did again when I came home from work a couple weeks ago and thought it looked to yellow/warm colored. so I boosted the white and blue. Then I also felt like the "moonlight" setting that I had out for about two hours at the end seemed too long and shortened that too. So this is the third adjustment, the 2nd was what I described earlier.

and I have no idea what the warm setting is up to, it must not have made much difference
 
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