# How much is too much light?



## geeks_15

I've been researching different lighting fixtures and setups on this and other posts recently. I've found plenty of posts about light fixtures with higher and higher light intensity. I thought it would be interesting to look at from the other side. How much light is too much? I was hoping we could discuss experiences when lighting has proven to be too much? 

Was algae out of control? Was the aquarium or hood overheating? Did you just get tired of too much maintenence from rapid plant growth? Or did you decrease the lighting and get an unexpected benefit?

There are many posts discussing the minimum amount of light. It may be helpful discuss the maximum amount of light. Please post your experiences, including tank size, lighting arrangement, and the problem.

Thanks,

Jeremy


(disclaimer: I know each tank is different and many variables factor into aquarium problems, but I still think this topic could be interesting and useful. )


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## jaidexl

Too much light can mean plenty of things that you mentioned. The first being that it outweighs the light/co2 ratio and produces more algae than anything. Another being rapidly induced uptake and growth, some of us including myself don't have the time to manage a tank like that without letting it slip away into deficiencies. I recently converted my highest tech tank (65gl) into a 1wpg - no CO2 low tech for this reason, also to combat a lot of algae that popped up after a move. Many of the plants in this tank started doing much better after the change, go figure.

I think half the plants listed as requiring high light would actually prefer around 2wpg of normal output light along with healthy nutrient and CO2 levels, as opposed to the 3+wpg that people here in the states are using so much, lately. I think many folks go into light shopping the way they enter an electronics store, and feel bigger is better when they're pouring money out of their pockets. This mentality creates a situation where the bulk of your free time will be used up by tank maintenance rather than sitting and enjoying the plants. I feel bigger is better in the sense of efficiency and options, that's why I stick with T5HO fixtures for average and large tanks. One of these with four bulbs holds more options than anything on the market aside from retrofitting. Better spread, easy to turn the power up or down, mess with color etc.


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## Philosophos

It's not just the wattage that's too high. Outside of LED, everything manufactured that I have seen with more than one bulb fails to space the lamps out correctly. I'm currently having to go a little DIY with my lighting because of the issue.

I don't know who advocates 3+ WPG but I haven't seen them here. I don't know how anyone can argue that 50mmol PAR is not enough light to grow their plant of choice. It works for nature, and is backed up by anywhere a successful 100% ADA spec tank exists.

The 65w over the 20gal in my living room is over lit. The growth is too fast, even when I slack on ferts. I wish I hadn't gotten so much light. Thankfully, the aquarium is being replaced with a 28 gal bowfront, and hopefully this will make for a little slower growth.

High light, when done at its best, will leave you trimming plants constantly. Algae will not necessarily happen if the CO2 is high enough, but it's definitely a stricter schedule to prevent it. If the level of light exceeds the amount of CO2 that can be provided without gassing the fauna, then algae will happen.

I see two purposes for overdriven lighting. First, commercial plant growth; you're going to be maintaining these things all day anyhow, so they might as well grow as fast and healthy as you can get them to. Second would be aesthetics; if you want a very bright tank because it looks good, then that's your own business. Personally I'd advocate finding a bulb that cranks out a lot of lux and less PAR in these cases, presuming it provides the desired color of lighting.

-Philosophos


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## jaidexl

Oh, I'm sure there are some of them here, if not go ask plantedtank.net how much light you should use on your 28. I don't doubt the majority of suggestions will say 3wpg, although there are plenty of folks picking up on the fact that you don't need so much to grow healthy plants, and that less light makes for a more laid back endeavor. It's still only been a few weeks since I ran across the last journal stating there was 4wpg being used.  Plenty of plant profiles are still suggesting 3 as well. There have been a few folks growing these 'difficult' species under less light to prove that it's not so.

As far as bulb spacing, Tek Lights and similar grow lights originally designed for indoor horticulture are about as good as linear fluorescents get, with wide and/ or multi-bend reflectors. Some are very pricey though, the Teks in particular, but that didn't stop me from getting one. Retro is definitely the first, best option for getting the most spread but the Teks don't leave much in the dark.


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## Philosophos

The same people who make Teks also make Sunblaze (sunlight supply I believe), which is what I'm going with for a larger tank. For narrow tanks, even the teks are a little too close together IMO. The sunblaze is all individual strips, with reflectors and hanging kits available. Not true parabolic for the reflectors, but close, and the price is very good on them. The only downside is that there's no housing for multiple strips; it's either canopy mounted or DIY hanging.

-Philosophos


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## niko

"Too much light" has to do with the way the plants handle the light. If the plants are blasted with 5 watts per gallon of any light and the water is kept void of nutrients guess what happens? Some plants still grow, and quite fast too. But not just pale - they grow transparent leaves.

In such high light and no nutrients algae is non-existent. The tank is sterile. Lowering the light causes the plants to not grow and algae steps in.

When discussing light would be best if we discussed spectrum perhaps. I'm not entirely sure that's the best way to look at light either but I think wpg, Kelvins and such are ridiculous. You can do things with a single 54 watt Giesemann Midday T5HO bulb that you can't do with 2x65 watts Power Compact bulbs. Of course the shape of the bulbs matters a lot, the reflector, age of the bulb, distance from the surface of the water, how tall is the water column, plant shading each other and so on.

One good experience to keep in mind: Plants do VERY well under 3-4 wpg of any light for only 2 hours a day and 22 hours of complete darkness. So the light period/light intensity maybe a very good thing to keep in mind.

--Nikolay


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## Philosophos

niko, I find your comments about 2 hours of 3-4wpg interesting. Is this something you've figured out your self, or is it from published work? Any resources on the topic?

-Philosophos


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## niko

Philosophos,

My own observation. I had a 40 gal. breeder tank with a 96 watt Power Compact bulb about 1-1/2" above the water surface. The tank was in a part of the apartment that had no light, no windows either. Basically the tank was lit from a computer monitor only if the PC was not on. I said that you could use "any light" in my first post because the PC I had was Chinese and cheap too - so no telling what spectrum. It was also about 2 years old.

I had quartz gravel in it. Water change maybe once a week, about 10%. No ferts. Moss, JF - regular and narrow leaf, tenellus, Val. nana, HC, crypts, glosso, marsilea, a few floaters. One Fluval 304.

For whatever reason I had the tank lit only 2 hours per day. May have been 3. A good amount of CO2.

Tank was completely clean. Even the HC held fine - better floating than on the bottom. Glosso grew small and slow. Mosses grew the fastest. There were 2-3 very small fish that I never fed.

Many of the plants disintegrated about 3-4 days after the CO2 ran out. That was my second observaton on how CO2 keeps plants alive even if the light is very little (short duration or just very low)

--Nikolay


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## Supercoley1

From what I have gathered in the answers in this thread are surprisingly open minded and well thought out. This is a huge surprise for an American dominated forum and I find it quite refreshing. Not even one person slamming suggestions of lower light achieving the correct results.

Let me add something for people to discuss :snakeman:

The answer to the first question is, there is no such thing as too much light that we can provide (within reason of course)

However we have to make sure that we supply the CO2 and nutrient to match the light. That is where it gets hard. Therefore if you add 10WPG you struggle 

Onto my thoughts!!!

I have seen the measurements of ADA prize tanks with 50mmol at the substrate and 150mmol at the water surface. Then I have seen measurements of tanks with 2 x T5HO full length tubes with independent reflectors in a luminaire (so they are both side by side over the centre) which is closer to 300mmol at the water surface and 100mmol at the substrate.

So compare the 2. 2 x T5HO is double the PAR of the ADA prize tanks that have lush HC lawns!!!! What does that tell us?

Answers on a postcard!!!!

My suggestion is 2 x full length T8s, retrofitted and not packaged together tightly in a luminaire. Each its own reflector and spaced a third from the front and a third from the back 'should' provide a nice evenish spread and 50mmol all over the substrate.

Why have people been banging high light on their tanks? because they like the pretty luminaires with tubes over the centre of the tank. Huge intensity directly under the tubes but you need that to make sure that the intensity is good at the rear and(more importantly) at the front. Why do they need intensity at the front? For their carpets!!!!

So better to have less light, well spaced and negate the need to blast the light in to get the intensity for your carpet 

Couple of things I did pick up on. Eek I await a barrage of abuse :lol: :



> age of the bulb


This myth needs binning these days. If your fixture has old magnetic ballasts then it probably does apply. The flicker start kills tubes pretty fast. If however you are using electronic ballasts (virtually all T5 and T5HO will have these) then from reports I have read the tubes lose 5% lumens over 8000 hours. Thats 3 years at 8 hours a day. Assuming that they lose PAR at the same rate then we should not need to be changing tubes every year!!!! 2 years? 3 years? 4 years even  Controversial?

Electronic ballasts are cheap these days and it is pretty easy to swap them for the old magnetic ones and that means for the price of 1 tube you get an electronic ballast. this then potentially saves you the price of 2 replacement tubes.



> Plants do VERY well under 3-4 wpg of any light for only 2 hours a day and 22 hours of complete darkness.


Indeed. Plants do very well under any light for any duration. Life is very adaptable and as long as things remain pretty constant you can get away with all manner of options that the myths say you can't  Also much easier to get high CO2 for 2 hours than 8  Blast it in for an hour and then turn it off. Job done. There will be more than enough from that 1 hour for the plants final hour.

I will shut up now because I use LED :lol:

AC


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## Philosophos

1/3 from the back? I've been sticking my lighting at the front half and farther forwards because of inverse square with intensity and the typically tall plants in the back. Boosting the light forwards also allows better penetration in near the base of the stems; where it's hard to keep that 50mmol.

-Philosophos


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## Supercoley1

That assumes there are tall background plants  those ADA tanks were virtually full carpets of HC with minimal height of plants 

You are thinking for yourself already with your positioning  Kudos for not going the pretty luminaire route :lol:

AC


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## Philosophos

Some ADA designs are, some aren't. For the iwugami-like setups, completely even is definitely the way to go.

After running one tank with a single CF, I'm never doing it again on any decent planted tank. The closest I think I'd ever get is multiple T5/T5HO single strips, as I'm doing now.

All the same, this confuses me:
http://www.adana-usa.com/images/gallery03/20.jpg

Notice who owns this tank, and how poor the distribution is. They're paying for it on the right, but the rest looks great.

-Philosophos


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## niko

Supercoley,

I'm not convinced that an electronic ballast keeps the bulbs working fine forever. My experience is with a popular ballast made by Fulham called Workhorse. It can be used to run any fluorescent bulb and it's electronic. PC bulbs ran with that ballast show visible wear (grey color at the base and diminished light output) after about 8 months of use. Granted the bulbs were Chinese.

About the distribution of the light:
I used to have a 55 gal. tank full of the healthiest Jafa Fern you have ever seen. The Fern grew extremely dense - when finally I pulled the plants out of the tank they felt hard like cabbage. The leaves were densely packed very closely to each other. The light could not penetrate everywhere, no way. But the strangest thing was to see fresh green leaves on the back of the plant. Basically the leaves in the front, close to the light where as green and healthy as the leaves on the back of the tank, by the bottom. Later I read about nutrient distribution and such but to this day I still don't understand how leaves can develop in complete darkness, never see the light, and still be fresh green.

This is my own picture of part of that tank. I photoshopped the background to make it black and increased the sharpness. But I have not fixed the green on any leaf. That's exactly how it looked. Imagine the leaves in the back looking the same.
http://www.aquaplantfarm.com/images/plants/javafern_03.jpg

The Fern had grown so dense that when removed from the 4 ft. tank it spread on a 6 ft. table. The thickness of this strip of Java Fern was about 4 inches. Length of the leaves was up to about 10". So imagine stuffing that amount of plants in a 4 ft. tank and having every single leaf grow and develop completely fresh green no matter where it grew. Hard to explain. Lights where 2x55 watt PCs 10 hours per day. Minimal fertlizing - a few drops of P once a week, and NO3 to read 2-5.

To be fair I have to say that no other plant thrived in this tank. The crypt that you see on the bottom right in the above picture never really grew. The hairgrass that you see at the base of the Fern barely spread.

And finally - to go back to the original topic of this thread - over that tank I also had another set of 2x55 watt PCs. When I turned on all 4x55 bulbs it took about 1 minute for the Java Fern to start pearling extremely heavy. The tank looked like it was boiling, not pearling. It was very ugly. That's what I'd call "too much light" - there is no need for it. To me the obsession over too much light comes from not providing other factors and trying to fix the mistakes using the light. Also trying to copy things blindly. And of course lack of patience.

--Nikolay


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## houseofcards

I don't totally disagree with most of the comments about light discussed here, but there are 'many' factors that determine how much light one would need. Height of tank, plant color and behavior are the three that stand out the most for me. Many tanks are tall, much taller than the ADA lineup and require stronger light to grow most carpets and to get good color on stome stems. I don't think the example of Java Fern is a good one since it will grow in most light situations. Also if you want plants to 'cascade' over rocks some require very strong light.


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## Supercoley1

> I'm not convinced that an electronic ballast keeps the bulbs working fine forever. My experience is with a popular ballast made by Fulham called Workhorse. It can be used to run any fluorescent bulb and it's electronic. PC bulbs ran with that ballast show visible wear (grey color at the base and diminished light output) after about 8 months of use. Granted the bulbs were Chinese.


I wouldn't say I was convinced about the 5% after 40% life statements BUT I do believe that run on an electronic ballast they last much much longer than the old electric/magnetic ones. If we were saying that tubes need changing every 6-12 months back then it goes without saying that it should be lengthened now that the majority of setups are using electronic.

The article I took the info off last year is linked at the end. Unfortunately they seem to have removed a superb comparison table from it which was what I was pointing to back then but this paragraph sums up what that table showed. Please note I am making the assumption that PAR falls off in reasonable equality to the Lumens however it may drop off more or less:

_Lumen Maintenance

A 400W probe-start metal halide fixture, with a ballast factor of 1.0, produces 36,000 initial lumens. A 6-lamp Super T8 fluorescent fixture, with a ballast factor of 1.18, produces about 21,950 initial lumens. How can this fluorescent fixture replace the metal halide fixture to generate 52% energy savings and still produce comparable light levels?

The answer is lumen maintenance. In review, lumen maintenance is an expression of the fraction of initial light output that is produced by a light source over time-typically at 40% of lamp life, which provides mean lumens. This determines the design light level.

Probe-start metal halide lamps experience a higher level of lumen depreciation than T5HO and T8 lamps. For example, a 400W metal halide lamp can lose 35% of its light output at 40% of life, while a T5HO or T8 lamp will lose only 5-6%. As a result, a 6-lamp Super T8 lamp-ballast system produces 11% fewer mean lumens for 52% less energy._

The link:
http://www.aboutlightingcontrols.org/education/papers/high-low-bay.shtml

AC


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## Philosophos

I thought it wasn't so much just being electronic, but also being programmed start rather than quick start that saved life?

-Philosophos


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## Supercoley1

thats getting technical. lol

Magnetic (electric) flicker starts and burns tubes out quickly.

Electronic instant starts does what it says. turns the tube straight on and it 'warms up' meaning it may come on at 80% brightnes and work its way up over several seconds to full brightness (like household CFs  ) Doesn't burn the tubes out anywhere near as fast as magnetic.

Electronic programmed /delayed starts again do what they say in that they delay the start and do the warm up first. Then they come on at near enough full brightness. Is a bit better than instant start electronic but much much better than magnetic.

Think of it like a car:

If you have to start it seceral times it uses a lot of petrol for not much worth (flicker start)

If it starts normally and you accelerate to 55mph it is reasonably efficient (instant)

If it magically started at 55mph without needing to accelerate then it would be perfect and always use less fuel 

AC


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## niko

This has to do with the original topic of this thread:





--Nikolay


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## Supercoley1

Philosophos will be aiming a wink at me there. lol

I've been speaking to defdac r.e. ading this to some info on barrreport as it adds another dimesnsion to the calculations we are making at the moment 

AC


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## geeks_15

Great info so far. Please keep it coming.

I'd also love to get some specific data.

For example, I had X amount of light over my 55 gallon and had too much algae. I decreased the light and the problem improved. This may help us zone in on a nice range light levels.

Or I had X amount of light over my 55 gallon and had to trim plants every week. I decreased the light and was able to trim only every 2 weeks.

Does anyone have such experience?

I don't because I tend to approach my lighting from the opposite end. I buy a fixture on the low end and add light until I'm satisfied. Here's my last tank data.

My last planted tank was a 29 gallon with 2 x 24" coralife double T5 bulbs. I added pressurized CO2 with a pH probe shutoff. I added little to no fertilizers. Substrate was ecocomplete. The tank was lightly to moderately stocked with small fish and heavily planted (no visible substrate from above). I grew mostly low and medium light plants with a carpet of lilaeopsis and faster growing plants included hygro polysperma and hygro corymbosa. I had very few algae problems. My plant growth was thick and lush. I trimmed plants every 2 - 6 weeks. I wish I had pictures but I lost them when my computer crashed.

I think a collection of this type of info would be very useful.


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## niko

I agree that a collection of personal experiences about light/plant growth would be great.

But I also know that a lot of people want the information short and don't even bother searching for it. 

The main thing to me though is something else. Very much eash one of us has had a tank that ran fine, plants were fine, algae were non-existent. And after a long time of this bliss all of a sudden things start to deteriorate. Despite no change in the maintenance. Despite everything being consistent. My point is - no matter how much we try to summarize and generalize our experiences we should not forget that we deal with living organisms. With an entire complex system of them in the boundaries of a glass box. So we could come up with a general list of advice, but noone should take it literally. Tom's Estimative Index is about the only approach that can be followed blindly because it's a shotgun approach to all problems. It's far from being the best way but it works very much every time.

--Nikolay


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