# What is the ideal amount of light for a new 70L tank?



## Wookii (14 Nov 2019)

I'm in the process of setting up a new 70 litre (60 x 35 x 40) tank for the first time after 16 years away from the hobby. The tank will be fully CO2 and EI dosed.

Whilst most of the set-up will utilise kit I already have, the lights will be new, so out go my old metal halides, in favour of cooler and safer (the tank will be in my sons bedroom) LED's.

The light I have ordered is the 32W Fluval Plant 3.0 - I love that this can be programmed for a full day/night cycle simply using my phone - something that took multiple lights and numerous timers on my tanks of old.

However, what I'm struggling to determine is what the correct level the light should be at - particularly for the set-up phase where the plants will be growing in.

The Fluval Plant 3.0 is specc'd at 2350 lumens, and reportedly has allegedly a PAR value of around 100 at 300mm and around 70 at 450mm.

Is this too much for a tank startup, and should I be looking to reduce the intensity?

Also, what I should I set the initial photo period at - I see recommendations from 6 hours all the way up to 12 hours?

Any suggestions would be welcome.


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## Edvet (14 Nov 2019)

Low tech ( longer hours, less intensity) or high tech ( shorter time, high intensity, CO2 needed)?


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## Edvet (14 Nov 2019)

https://tropica.com/en


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## jaypeecee (14 Nov 2019)

Hi @Wookii 

You have raised the $64,000 question! I couldn't find any reference to PAR at:

https://www.fluvalaquatics.com/us/plant-spectrum/

But, I am in a hurry - so please correct me if I'm wrong. Furthermore, the information presented is odd, to say the least. The primary colours of light are red, green and blue. Yet, one picture shows sliders for pink (!) and blue. Where's the green? And the spectrum shown is lacking in red light around 650 nanometres.

Just my initial thoughts.

JPC


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## alto (15 Nov 2019)

Not one of my favourite lamps but perhaps 3.0 has addressed previous design flaws ... it’s “value” rather depends on local cost/warranty
Regardless it should provide sufficient light for an 30-40cm tall aquarium, just check for shaded areas before you commit to a scape design

Cory at Aquarium Coop has done review videos on various versions of this light (no idea how the UK vs US versions differ) including some rough  PAR measurements (view qualitatively) ...
more on this at
plantedtank.net


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## Tim Harrison (15 Nov 2019)

Aside from all the technical mumbo jumbo, I'd just start on 50% intensity for 6hrs a day, a least for the first week and gradually increase it to around 60-70% intensity by 5% a week thereafter. Then see how you go at that light intensity.

As I'm sure you can remember it's a game of balancing the requirements of the plants against those of algae; most folk use way too much light which often favours the latter particularly if you're inexperienced or using a new light. If you want still more intensity increase by 5% per week, and watch for signs of nutrient deficiency and algae.

I usually wait till the plants have established and are growing well before gradually increasing the photoperiod to 8 hrs a day. By then the tank should have enough biological stability and wriggle room to absorb some mistakes. For most of us there is little point increasing the photoperiod beyond 8 hrs, since the plants won't benefit much but algae undoubtedly will.


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## Wookii (15 Nov 2019)

Sorry guys, I wasn't getting notifications from this thread for some reason . . . I'll sort replies now.


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## Wookii (15 Nov 2019)

Edvet said:


> Low tech ( longer hours, less intensity) or high tech ( shorter time, high intensity, CO2 needed)?



The tank will be high tech, CO2 injection, and EI fert regime.


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## Wookii (15 Nov 2019)

freewolny said:


> The correct level of light depends on the plants you'll keep in your tank but as a rule of thumb I'd say 1W/L no matter if it's HT or not.
> 
> And I've never cared about initial photo period (and initial intensity of light) - I keep it at full power for 8 hrs.



Thanks - is that 1W per Litre based on LED or T5's though?


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## Wookii (15 Nov 2019)

Edvet said:


> https://tropica.com/en



Thanks for the link - are you recommending the video or the app there?


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## Wookii (15 Nov 2019)

jaypeecee said:


> Hi @Wookii
> 
> You have raised the $64,000 question! I couldn't find any reference to PAR at:
> 
> ...



The PAR rating I saw on another forum from someone who has called Fluval and ask for that data. It could be baloney, but I have no reason to question it as such.

I believe the Red and Blue LED's supplement white LEDs - obviously the main component of white is green, so I think the green is covered.

Good point on the red on that graph. I have the unit here now though (it was delivered this morning) and it's certainly seems capable of producing a colour temp with plenty of red in it.


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## Wookii (15 Nov 2019)

alto said:


> Not one of my favourite lamps but perhaps 3.0 has addressed previous design flaws ... it’s “value” rather depends on local cost/warranty
> Regardless it should provide sufficient light for an 30-40cm tall aquarium, just check for shaded areas before you commit to a scape design
> 
> Cory at Aquarium Coop has done review videos on various versions of this light (no idea how the UK vs US versions differ) including some rough  PAR measurements (view qualitatively) ...
> ...



Thanks for the feedback. It's value to me is the automation and flexibility to be honest. To my fault I haven't really shopped around to much to look at alternatives. Would you suggest any other models?


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## Wookii (15 Nov 2019)

Tim Harrison said:


> Aside from all the technical mumbo jumbo, I'd just start on 50% intensity for 6hrs a day, a least for the first week and gradually increase it to around 60-70% intensity by 5% a week thereafter. Then see how you go at that light intensity.
> 
> As I'm sure you can remember it's a game of balancing the requirements of the plants against those of algae; most folk use way too much light which often favours the latter particularly if you're inexperienced or using a new light. If you want still more intensity increase by 5% per week, and watch for signs of nutrient deficiency and algae.
> 
> I usually wait till the plants have established and are growing well before increasing the photoperiod to 8 hrs a day. By then the tank should have enough biological stability and wriggle room to absorb some mistakes. For most of us there is little point increasing the photoperiod beyond 8 hrs, since the plants won't benefit much but algae undoubtedly will.



Thanks Tim, that makes sense and sounds like a plan. Triggering a massive algae outbreak is what I'm hoping to avoid - though I'm under no illusion that algae wont appear somewhere at some point, and to be fair I consider it part of a natural aquatic environment as long as its not too unsightly. At the same time I want to ensure I have sufficient light for the carpet plants to establish . . . a balancing act like you say.


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## Tim Harrison (15 Nov 2019)

A lot of scapers use the TwinStar 600s series coupled with this inexpensive controller including myself. The light is relatively inexpensive and comes in tank mounted or pendant form, and has an amazing colour rendition that makes the colours of plants and critters pop.

The Twinstar light in use over NatureScape, on at 60% intensity and photoperiod 6 hrs/day. The carpet is MC...


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## Wookii (15 Nov 2019)

Tim Harrison said:


> A lot of scapers use the TwinStar 600s series coupled with this inexpensive controller including myself. The light is relatively inexpensive and comes in tank mounted or pendant form, and has an amazing colour rendition that makes the colours of plants and critters pop.
> 
> The Twinstar light in use over NatureScape, on at 60% intensity and photoperiod 6 hrs/day. The carpet is MC...



Thanks for the links Tim. That is a beautiful looking tank! What is the size?


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## Tim Harrison (15 Nov 2019)

Thanks, it's an ADA 60-P, so 60x30x36(h)cm.


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## Edvet (15 Nov 2019)

Looks far higher than deep...........wide angle lens?


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## Edvet (15 Nov 2019)

Wookii said:


> are you recommending the video or the app there


The video. ( i was suspecting it to be a low tech tank, it being in your son's bedroom)


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## Wookii (15 Nov 2019)

Edvet said:


> The video. ( i was suspecting it to be a low tech tank, it being in your son's bedroom)



No, I have much of the kit for a high tech set-up from my previous tanks, and most of it can be store neatly under the tank so its not an issue that its in his bedroom.


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## Tim Harrison (15 Nov 2019)

Edvet said:


> Looks far higher than deep...........wide angle lens?


I think mostly the angle Ed. The image was taken on an iPhone 8.


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## jaypeecee (16 Nov 2019)

Tim Harrison said:


> Aside from all the technical mumbo jumbo...



Hi Tim,

To which 'technical mumbo jumbo' are you referring?

JPC


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## Tim Harrison (16 Nov 2019)

The often spurious claims of manufacturers


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## jaypeecee (16 Nov 2019)

Tim Harrison said:


> The often spurious claims of manufacturers



Hi Tim,

Couldn't agree more. But, it's worse than that. Some manufacturers treat their customers with disrespect. The more specialized the product, the more they pull the wool over the eyes of their customers. In so doing, they ignore the fact that some customers design the type of product that they are selling. Of course, it's not just aquatics. The story's the same across other business areas.

JPC


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## Wookii (11 Dec 2019)

Just to extend on my initial question, with a couple of follow up questions if I may:

1.  If I set my lighting for a sunrise/fade in and sunset/fade out, how does that affect the chosen photo period? For example, say I have a 1 hour period for each, should that 2 hr period be considered a 1 hour contribution to the total photo period (given the average 50% of selected max light)? Or does in not work in a linear way like that?

2. In the absence of being able to measure the physical par values, if I raise the light 300mm above the tank (rather than its default position of resting on the tank rim) how does that affect the level I should initially set the lighting to? For example if I follow Tim's recommendation above of an initial 6 hour photo period at 50% light intensity, does that recommendation change if the light is higher, or not?


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## Edvet (11 Dec 2019)

1) remember algae can profit from lower light values then your (other) plants, much lower. So i wouldn't start using sunrise/sunsets till all is growing very healthy. So 2 hours added are 2 hours added for the algae.
2) Raising will lower lightvalues squared to distance, double the total distance will give 1/4 of the light.https://petapixel.com/2016/06/02/primer-inverse-square-law-light/. Less light longer time can work in low tech tanks for instance ( so lower light, no CO2 needed), within reason. Low tech tanks can work in 12 hour light even, just not in high light ( unless you are prepared to use large amounts of stable CO2 levels)


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## Wookii (11 Dec 2019)

Edvet said:


> 1) remember algae can profit from lower light values then your (other) plants, much lower. So i wouldn't start using sunrise/sunsets till all is growing very healthy. So 2 hours added are 2 hours added for the algae.
> 2) Raising will lower lightvalues squared to distance, double the total distance will give 1/4 of the light.https://petapixel.com/2016/06/02/primer-inverse-square-law-light/. Less light longer time can work in low tech tanks for instance ( so lower light, no CO2 needed), within reason. Low tech tanks can work in 12 hour light even, just not in high light ( unless you are prepared to use large amounts of stable CO2 levels)



Thanks for the reply Edvet - good point on the lower light levels, I hadn’t thought of that. I’ll save the sunrise and sunset for a couple of months then.

On the light levels vs distance, thanks for the link - I should have known that really given time I’ve spent setting up projectors in the past! 

If I use reflectors to limit the light spill/beam to the surface area of the tank, the same area as if the light was at the tanks surface, presumably that narrowing of the beam of light reduces the losses to less than 75% per doubling of distance? (Though I appreciate there will still be losses as they won’t be ‘perfect’ reflectors)


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## Edvet (12 Dec 2019)

Well the inverse square law will still work, just with reflectors you increase the original output, just like LED's  with a directional output give higher light to start with.


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