Having trouble with the math ...

[trennamw]

How much of this would I want to add to a traditional 29 gallon aquarium, to keep it "medium" light level?

It's 6500K color temperature, 100 lumens per foot of lights.

LED Strip Lights

If I'm calculating from the Marineland brochure correctly, the LED I currently have is rated for about 240 lumens, 7 par at 12", 2.5 par at 24". Color temp unknown.

 

[icydeath]

Freshwater or saltwater?

I assume saltwater because of the LED's.

 

[trennamw]

Freshwater. LEDs just because that was the higher quality aquarium kit at Persmart when I decided to build my first tank and didn't plan to do plants.

Oh and the led strip lights because it's $10 and not a lot of effort to add more light to my existing hood.


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[icydeath]

Since it isn't planted and freshwater, I would go ahead and get it. Then use electrical tape and tape the LED's to your hood. Keep changing how many you use till you like it. Trial and error! I would buy one strip. That will be more than enough IMO. HOWEVER you should take a look at this video

Also you could invest a little more and get these lights

If you watch the video you will understand why.

Get this:
3m
30leds/m
waterproof
44k IR +2A power

Really amazing tank lights, especially for the price.

 

[Fresh2o]

I stink at math but like problem solving. I may be way off but here goes...
Okay, as you stated from the marineland brochure, PAR is 7 at 12" and 2.5 at 24". I'm thinking that a 29g is about 18" tall. Thus, the PAR would be the average of the PAR at 12" and 24" which would be 4.25 PAR. Let's round the to 4 PAR. According to the link below, medium lighting is 35-50 PAR. To achieve the low end of that range, you would need about 9' and for the high end, about 12.5' of the Marineland light. Since the new light you are looking at is about 100 lumens per foot and the marineland light is 240 lumens per foot, then you would need 2.4x more in feet for the new light to match the marineland. Thus, 9' x 2.4 = 21.6' and 12.5' x 2.4 = 30'.
Therefore, you will need between 21.6 - 30 feet of the new light.
Please somebody check my math!!!
Based on the prices, 16' and 5' lengths will be about $48 ($30 + $18 for the low end) and roughly two 16' lengths would be about $60 ($30 + $30 for the high end). So, this is less than most LED fixtures that will provide medium light in a 29 such as the Finnex FugeRay Planted + ($80 something). Next thing I would do, regardless of the numbers, is search for product review on the new light.

Reference:
Lighting an Aquarium with PAR instead of Watts : http://www.plantedtank.net/forums/showthread.php?t=184368

 

[trennamw]

Sorry I wasn't clear. The tank is planted. I want to expand my plant selection to include medium light plants.


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[icydeath]

I gotcha fresh2o.

4.25 PAR and assuming we aim for >35 PAR
35/4.25 = 8.2352 then round up to 9... So just as a little bit of extra info, your par is 4.25*9 = 38.25 So you are in the middle of the low end range.
50/4.25 = 11.7647 then round down to 11, so you stay within the range. your par is 4.25*11 = 46.75

8.2352*2.4 = 19.7644
11.7647*2.4 = 28.2532

You probably have to buy it in full feet so you would round up your feet to 20-29 feet of the light. Remember to change your fert dosing and CO2 dosing based on the lights and use algae growth as a tip (if algae starts growing, tone down both a little) you want to find your sweet spot. You can also alter the photo period instead of changing ferts and CO2. Much easier. Try doing by increments of 30 minutes and find that golden range!

Good luck with your medium light! - Raymond

 

[icydeath]

1 20M RGB 5050 SMD Waterproof 300 LED Light Strip Flexible IR Remote 12V Power | eBay

These LED's are cheaper and they are 13 lumens per LED if you have 30 per meter than it is 390 lumens per meter or 3.28 feet

390/3.28 = 118.9024 lumens per foot.

240lm/118.9024lm

So using the PAR footage,
8.2352*2.0184 = 16.6224
11.7647*2.0184 = 23.7466

Then find that in meters: 5.0678-7.2398

So to be safe you want to round up from the lowest range and round down from the highest range.

So, 6-7 meters.

About 32 dollars for 6 meters and 34.50 dollars for 7 meters.

Cheaper, and the colors change with the controller and you can dim the lights along with other functions. Pretty cool if I do say so myself.

Remember these settings:
Length: 2x3m or 3m, 4m
LED Quantity: 30leds/m
Type: waterproof
Parts: 44k IR +2A power.

... That took a while but I got it!

Good luck on your diy lights! - Raymond

 

[trennamw]

Thank you all so much!

Especially for correcting my largest mistake... I thought the lights I was seeing were $10 for 16 feet! Lol.

I'll also be moving the aquarium from a fully dark room to One that is quite light. So I will have some experimenting to do, to be sure.

Does anyone have a guesstimate on whether I can balance medium lighting with a heavily planted tank, root tabs, Excel, and equilibrium? (The equilibrium is because my tap is almost like distilled water). I want to avoid co2 injecting.

I'm aiming for a low tech tank and just want to expand my plant selection possibilities a little. Maybe I'm barking up the wrong tree ...


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[Fresh2o]

My brain still hurts from all of the numbers. Icy death did a great job figuring it out. As for medium light, heavily planted with no injected CO2...it can be done. For the longest time Rivercats ran T5HO, LEDs, and metal halide over a 220 g and used Metricide instead of Excel and had great results.
Since the DIY is dimmable, you can ramp it up slowly as needed.

 

[trennamw]

And I can't quite tell if any of you figured that I'm keeping the current light and adding to it? Please don't bother yourselves to redo the math I'm just wondering.


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[trennamw]

Also, what I haven't been able to extract from the calculations you all did ... It looks like there's a factor you're using for converting lumens to par? I can't quite pull it out of your calcs though. That's where I got stuck after two hours on the net last night, was the new lights being in stated in lumens not par.


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[Fresh2o]

And I can't quite tell if any of you figured that I'm keeping the current light and adding to it? Please don't bother yourselves to redo the math I'm just wondering.


Sent from my iPhone with three hands tied behind my back.

I kind of figured that out afterwards. Whichever extra light you choose, you could put it on a separate timer and adjust the duration as needed. Dimmable is nice. 6500K is nice as well.

 

[icydeath]

Lol I also found that out after I did it but that is easily modified.

240 Lumens at 18 inches high has a PAR of 4.25. 12" = 7 and 24" = 2.5

It is also 11 inches long I think.. You should check that.

So... That means that you need to get the end result of feet or meters, multiply it by 118.9024. Then you subtract 240 lumens, then divide 118.9024 from the end result. Lucky for us 118.9024 go into 240 well so we can have a cleaner rounding as an end result.

Let x equal the low end and y equal the high end

[(118.9024*5.0678)-240]/118.9024 = x
[666.7808-240]/118.9024 = x
426.7808/118.9024 = x
3.5893 meters = x

[(118.9024*7.2398)-240]/118.9024 = y
[860.8295-240]/118.9024 = y
620.8295/118.9024 = y
5.2213 meters = y

So round up x and round down y and you get 4-5 meters. So pretty cheap lights if you use the link I gave you.

Then go as high as whatever lights you choose go, and slowly dim downwards until you have no algae growth. You may have to edit a little as plants grow, but you should be good to go because you have dimmers.

Best wishes! - Raymond

 

[trennamw]

I am sorry I still am not following ... I'm pretty darn smart I just don't understand the steps.

Maybe you can walk me through just this much ... How much PAR is likely, 18" away from 100 lumens?


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[icydeath]

Hmm... Not sure if we addressed that correctly actually... LOL

Okay so 240 lumens = 4.25 PAR at 18 inches... Now you want to divide the PAR of 240 lumens by the efficiency coefficient which is 240 lumens/blank lumens
1. Therefore, you would divide the PAR by 2.4 if you are using the Saltwater led's and have 100 lumens per foot divide 240 by 100 to get 2.4 (the one you posted)
2. If you use the one I am suggest, you divide the PAR by 2.0184 because you are using 118.9024 lumens and divide 240 by 118.9024 to get 2.0184

So...

1. 4.25/2.4 = 1.7708 PAR
2. 4.25/2.0184 = 2.1056 PAR

Now you have to re do some steps...

1. 35/1.7708 = 19.7560
50/1.7708 = 28.2358
2. 35/2.1056 = 16.6223
50/2.1056 = 23.7642

So for the first led set you need 20-28 feet

And for the second you need 5.0664-7.2433 meters So round up the 5.0664 and round down the 7.2433

So 6-7 meters. Weird... lol about the same answer for both of them.

Hope that made sense! - Raymond

 

[Fishperson]

Dang. Crazy math going on here. Props to you Raymond I'd never have figured this stuff out!

 

[trennamw]

Thank you so much!! I'm getting it now.


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[icydeath]

Haha thank you.

I usually don't do this for my tanks however LOL I really should... XD

 

[trennamw]

So maybe I can play along now ... and do some closer calcs on my existing light.

I'm actually *estimating* the existing light. Marineland's brochure doesn't give the PAR for its hoods. But it says it has 42 of the 60mW white LEDs that are also in its "Single Bright" light.

The Single Bright that has 51 of these same LEDs is 8 Par / 790 LUX at 12", and 3 Par / 250 LUX at 24". I have 18" between the lights and substrate. So ... average the two is about 9.5 Par / 520 LUX.

9.5 Par / 520 LUX ... divide by 51 bulbs in their Single Bright light, times 42 of the same bulbs in my LED hood ...

My existing light probably has about 7.8 Par / 428 LUX. And lumens, if the Marineland brochure is correct, is likely about 276.

Now. I suspect the Marineland brochure isn't quite right, in part because of all the other variables (light in the room, reflection off substrate, density of plants) ... and in part because they say the LED hood is 990 Lux.

So I'm in "very low light" land, with some happy crypts but non-growing anubias and java fern.

I'd like to shoot for the low end of "Medium", because it will be a low tech tank, in a room with a lot of indirect sunlight, and the substrate is white, and the photoperiod long. (Stuff we learn in Oregon - you can grow "full sun" plants in part shade due to our looooong summer days, especially if they are by a white wall or light colored mulch).

So ... I need another 22-23 PAR.

Sooooooo ... (rolling up sleeves ) ... given ....

240 Lumens at 18 inches high has a PAR of 4.25

22/4.25 = 5.17 of that unit.

5.17 x 240 lumens = I need another 1242 lumens. Ish. So, I should go for about 13' of the one, or 11' of the other.

Unfortunately, the idea was to just stick these to the underside of my existing tank hood, which is 30" long. I *might* be able to fit 4 strips, but it's rapidly becoming impractical given the requirements for linking multiple strips together and making the whole thing waterproof (it is wet under there).

The video above (thank you) is illuminating (har har) ... I'd not love that look, but I could "hack" this IKEA coffee table ... LACK Coffee table ... the top is very lightweight, and wouldn't be difficult to turn into a snug-fitting lid over the glass lid. It's getting more expensive than changing lights but it's more interesting too