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ADA lighting at Aqua Forest and nice low PAr values-who knew?

Discussion in 'Lighting' started by Tom Barr, Oct 26, 2008.

  1. elwaine

    elwaine Junior Poster

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    What an outstanding forum! I just joined yesterday and have spent over 12 hours reading threads here... and this is one of the absolute best. Taking a scientific approach to the hobby - what a wonderfully refreshing concept.

    So if I want to maintain my photoperiod but reduce plant growth rate, can I reduce the effective wattage simply by adding a diffusing screen between my lights and my aquarium, without having to worry about blocking certain wavelengths via the diffuser? Or am I better off trying to find a lower wattage lamp. (I'd hate to have to replace my entire fixture.)

    Thanks in advance - for this forum, and for your help.

    Larry
     
  2. Gerryd

    Gerryd Plant Guru Team
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    Larry,

    Not sure what type of fixture you have, but can you remove a bulb or so to reduce the light?

    There are some cheap and easy ways to hang lights if you look around w/o having to replace your fixture.

    Can you provide some more details?
     
  3. Tom Barr

    Tom Barr Founder
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    Yes, you can do that, or raise the light, or as Gerry mentions, reduce the bulb no#(not always a good method- see further for why).

    If you have say 4 bulbs, then turning off the inner two inside bulbs works well.
    But if you only have 2 bulbs or worse........only 1, then you do not get a wide spread of light and only the tops of some plants will do well in the back etc or front or middle depending on where you place it.

    If you have each bulb at 2-"3 from the front and rear, then you maximize the light strike and get thicker fuller light penatration.

    Regards,
    Tom Barr
     
  4. elwaine

    elwaine Junior Poster

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    Thank you for the replies.

    I've two lights in mind: One is a Current PC 12" fixture with an 18 Watt dual lamp - 6700K and 10,000K. It sits 4" above the water over a 3 gallon planted Pico. I can't easily elevate the light. The only bulb change option is to switch the lamp for a 10,000K /Actinic combo lamp. Based on area, I think I have moderate light at 6 Watts/gallon. But I'd like to reduce the light output to help control algae and make it easier for me to use ferts and control CO2.

    The larger tank (18 gallon 60 cm) has a Coralife PC fixture with 2 X 65 watt 6700K lamps. I never intended running both lamps, so that tank (based on area) also has moderate lighting at about 3.5 watts/gal. I bought the fixture because it has legs that tilt the fixture up and out of the way when gaining access to the aquarium. It sits 4" above the water and I can't easily elevate that fixture either. I could replace the 6700K lamp with a 10,000K lamp, but I'm not sure that will accomplish much.

    In the meantime, I'm going to try clear "Con-tact" plastic, which is actually slightly frosted and not clear when applied to the acrylic screens of my fixtures. I don't have a light meter as such, but I do have cameras and will see how my quasi opaque diffuser alters f stops.
     
  5. Coralite

    Coralite Junior Poster

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    I suspect that part of the reason for you registering such low par values is that you were using a flat field light sensor which really only accurately measures light which falls within 90 to 75 degrees to the sensor. Had you been using a spherical field light sensor (which looks like a light bulb) I suspect you would have registered light values up to 50% higher. So a reading of 50 mmol on a flat field sensor would probably be closer to the 70 mmol neighborhood when using a spherical field sensor. There is a big difference between 50 and 70 mmol in my book.

    The difference between using the two sensor types is less of an issue with non-point source lighting such as fluorescents but when dealing with point sources like halides (especially with the puny, ineffective reflectors most people use), there is a complicated interplay of construcitve interference.

    When using a spherical field sensor you will get higher par values near the substrate than you would about half way up the tank and you will find hotspots of light in between halide reflectors that are higher than right under a single reflector.
     
  6. evandro.carrenho

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    I have two questions based on the latest posts:

    1- Do you get higher PAR readings at the substrate level because of light being reflected on the glass back to the water? I think VaughnH mentioned this effect in other threads.

    2- When bulbs are raised, there is a higher "air" column for light to cross. We now that PAR readings decrease a lot as the the water column gets higher, but can we say the the "air" column can be neglected in terms of decreasing the PAR readings? I ask this because once I suspected that carpet plants were suffering in my tank as I raised the lights. Although this causes some light to spread outside the tank, it seemed to me that the light that remaining within were not punching down to the substrate.

    Thanks,
    Evandro.
     
  7. Coralite

    Coralite Junior Poster

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    The higher light values near the substrate has to do mostly with constructive interference. When using just one halide bulb, this is due to reflection from the glass and the substrate, and sometimes the design of the reflector itself. When using more than one halide bulb this is mostly due to overlapping light fields.
     
  8. VaughnH

    VaughnH Lifetime Charter Member
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    As I recall my physics courses and work experiences, you can only get interferrence with light if you have very narrow beams, which are identical in every respect. You won't get that with any light we use on an aquarium.

    Also, light intensity from any of our types of light does drop with the distance from the bulb, whether the light passes through air or water. With water you get slightly more loss due to the water absorbing some of the light. But, it is the simple geometry of the system that gives the loss versus distance. If it were possible to use a perfect point source of light, a parabolic reflector could give a parallel beam of light so that the loss with distance would be very slight within the beam.
     
  9. Coralite

    Coralite Junior Poster

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    What you are talking about is destructive interference which is highly improbable in our tanks and as far as I know it is only relevant with lasers (when light is concerned). The phenomenon which I am discussing is construcitve interference which is an important factor governing light fields for aquaria, especially with point sources of light.
     
  10. VaughnH

    VaughnH Lifetime Charter Member
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    No, interference occurs whenever the two very narrow beams are identical and in phase with each other. If one of the beams is slightly deflected or takes a slightly longer path, when you combine the two beams you get interference patterns from which you can determine what caused the interference. What you call constructive interference is simple addition of intensities from two different sources, or with reflected light added to the direct light. Put two identical bulbs above an aquarium and you get approximately double the intensity. That isn't interference. Add a reflector to increase the amount of the emitted light that reaches the substrate and you also get an increase of intensity, again not interference, but simple addition.
     
  11. SuperColey1

    SuperColey1 Guru Class Expert

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    Tom may have read over on UKaps me questioning the high light plant/low light plant theory for a while nows and indeed I did suggest that I suspected it was more to do with the CO2/Fert levels that are applied in higher light tanks. Many poo pooers though especially with 'carpeting' plants.

    Good to read something I 'speculated' at could actually be right.

    Although I do have 'supposed' low light plants I get rampant growth to the point that I am constantly having to hack away at the plantmass to keep it to the jungle style.

    Just a quick pic and the stats of my tank:

    Tank 125Ltr (18" tall)
    Lighting : 0.9WPG T5HO 4500K for 8 hours a day. 0.5WPG T8 6500K for the central 2 hours
    CO2 : pressurised injection stable at 30ppm
    Ferts : Full EI (as per high light quantities)
    W/C : 50% weekly
    Circulation 17.6 x tank volume per hour (2200lph)

    And this is the tank after its weekly heavy prune!!!
    [​IMG]

    I wish I had any money to spend on testing equipment so I could back up my own theories but alas the recession has left me with no money and no job. lol. So that backward move for scientific discovery will have to wait ;)

    Many thanks for the thread Tom. Interesting reading for many. Keep up the good work.

    AC
     
  12. Tom Barr

    Tom Barr Founder
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    Well, you got it right and now you can run around a tell everybody:p
    I've speculated many things............but they really are not ideas I can support, so they are mere musings..................

    I need evidence.

    I need to be somewhat sure that the results I get and the methods will give me the results I feel are fairly well supported.

    I figure measuring 6 ADA tanks that all look decent, one was placed 20th overall with stiff competition and lots of classically claimed high light plants like HC, tennellus, Gloss etc makes the point well.

    We assumed that all HQI and all PC lights are roughly the same, this was not true in this case.

    With a rep of 6 tanks, it's fairly safe to say that the ADA are more for looks and really are very poor as far efficiency. Whether this is on purpose, or trial and error on ADA's part.......I cannot say. It's often dangerous to try and out think marketing and public's desire for "more is better", particularly if someone like me bothers to to test the product only to find that it has a conservative rating of 2X worse PAR output as other brands using the same bulb. I guess if you tell folks enough baloney, they will believe and not check to see if what you say is true.

    One of those choices had to be made, either ignorance and not checking themselves, which scares me.............or they did it on purpose, which also scares me..........they are supporting the myth that high light is required and to telling you why their's works so well.

    Either case is does not place ADA in a particularly nice "light". Is there a third option? I suppose using a poor method to measure light could have been done, but even there, it would not have been a factor of 2-3x off.

    So........I'm left with some serious doubts about ADA. I like them and all, do not get me wrong........but some of it is just BS. But many take it as absolute truth:rolleyes:

    Regards,
    Tom Barr
     
  13. Tom Barr

    Tom Barr Founder
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    I already have a LiCOR 193:cool:
    So it's not something I cannot compare and have not already in some situations.
    In the columns at the lab, there's not much difference between them. We use MH's there also. We also have vaults that are 4ft deep and use 3 x 400w MH's similar.

    The Apogee flat sensor PAR readings are also the same within about 5 micromols with the HQI as they are with the PC bulbs as well and with the combo mixes also.

    No, not when I have the equipment you mention that supposely gets around the issue and is at least according to your speculation, able to show the differences you are suggesting here.

    I will go to AF and measure it, then we will know if there is a difference.
    I know this from my own work at the lab, but I might be wrong also. Still, the non point sources also have the same ranges as well. You can say something about the HQI's, but not much about the PCs and what about the HQI+PC's?

    I'm not so sure.

    The other issue is where you measure, I measure at the tips of the plants(this changes through space and time in every tank), as well as various distances and locations around the tank for Hot spot issues.


    Well, we shall see. I have doubts anyone here has used the LiCOR sensor or on any forum other than a few reef tanks and then mostly in the open water as research, rather than in tanks except perhaps Monterey or Long Beach Aquarium etc.

    Even so, what applies there does not apply directly to the ADA tanks in question or their reflectors etc. I can measure and often do address such issues in space when I measure light. The plant tips is often where I first measure, then go after the within the beds, and then within the water column.

    The sensor for LiCOR is rather large and bulky, the flat sesnors are quite useful. Still, a good comparision between those and the LiCOR sphere will address this more definitively. Know any plant folks willing to pay for the LiCOR?
    I don't.

    Then we will know and not guess specifically on ADA's lighting with 6 of their aquariums. Not many folks have such access to that many of their tanks and the faithful rarely show up to ADA in Japan with such equipment:eek:

    Regards,
    Tom Barr
     
  14. Coralite

    Coralite Junior Poster

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    So were you using a flat-field or spherical sensor?
     
  15. Tom Barr

    Tom Barr Founder
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    Do not fear, next Monday I'll stop by with the Licor 193 and settle the issue.
    This should placate any criticisms.

    If not, you can go down to AF yourself and measure it with whatever you think will do the job correctly. Talk is cheap. Support the issue: measure and test it. Look into it and see. Then set up the test to measure it in the case that is specirfic to your question, the ADA lights.

    I'll do paired test using the Apogee flat with the LiCOR 193. I have a LiCOR datalogging meter I'll bring.

    Won't take long to obtain the measurements, that's the nice thing about stable fake lights vs the sun:D I hated spending all day measuring lakes light, O2, CO2 etc.

    Aquariums are so easy and stable.

    Regards,
    Tom Barr
     
  16. Coralite

    Coralite Junior Poster

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    I used to do so many P/I curves that I used to sleep with a Li-Cor under my pillow.

    I think the inefficiency you saw with the PAR readings at AFA is partly due to the tiny, puny, inefficient reflectors that are in the ADA fixtures. As a general rule, the larger the reflector the more homgenous the light field so the ADA fixtures could be expected to perform poorly at directing and homogenizing the light field.

    If anyone has ADA fixtures or bulbs that I could borrow, Sanjay Joshi has asked me to find some for him to test and thoroughly evaluate. It would be nice to elminate all this speculation and get some hard numbers on these widely used products.
     
  17. Tom Barr

    Tom Barr Founder
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    Well, the reflectors seemed little/no different than the ones on the Coralife.
    The flat sensor would be similar for the other brands unless the reflectors where radically different, yet in every case, they where not including the non point light sources............

    So I am a bit skeptical. Does not matter really, the 193 and the Apogee comparision will tell in situ for 6 nice well displayed ADA full set ups.

    I can run the sensors at the lab today to show the differences in the vaults at 60cm distances from water surface and at sediment etc. I'll report back later today.


    That alone will be telling. Bulbs are the same, reflectors looked the same etc. The main difference might be the ballast which is what I've suspected all along.

    We can rule out the bulb, reflector etc.
    All that's left is the ballast really.
    The reflector issue can be resolved by swaping the ballast(I have several) and comparing the 193 vs the Apogee at Aqua Forest.

    Then it's done.

    You also need more than a single replicate to say much.
    6 ain't bad without going to Japan.

    As far as meter differences and sensors, the lab should suffice there.

    Regards,
    Tom Barr
     
  18. Tom Barr

    Tom Barr Founder
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    Well, the fixture and reflectors are not the same sizes as the ones I compared these initially to: 9x6 by 2" deep for the Coralife, 6x5x2" for AB, the AB are similar....so the there's some difference in reflector sizing, but the light is still the same in the water at the same distances for the Coralife vs the AB. Maybe there's a difference with the ADA reflector.

    Still, what would change it by 2-3x PAR factor?

    120 vs 40 micromol?

    That's the same for the AB and the Coralife in single and multi HQI set ups here.
    If it was say 40 vs 50 or 60, then some errors etc perhaps, I could live with that.
    It was the same relationship through out the ranges measured, not just at the sediment also.

    In otherwords, is was a general trend.

    Regards,
    Tom Barr
     
  19. Tom Barr

    Tom Barr Founder
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    Okay, the comparison differences are as follows: we taped the sensors together about 3" apart on a pole and descended into the columns and either side of the columns as well as the center. The lights are Venture 5500K 400W all with mogul sockets.

    We did 6 tanks from 0cm, 10cm, 25 cm, 50 cm, 100cm and 150cm.

    LiCOR 193 : Apogee (units are in PAR micro mol/ m^2/sec)
    These are the averages of 6 reps and the variation is extremely low(+/-5-10micromol) These are for the center measurements, the sides where lower, but the same scale and differences.

    Surface 380: 382
    20 cm 180: 180
    40 cm 110: 105
    60 cm 70: 68
    100 cm 29: 27
    150 cm 16: 15

    So.............

    Now, what about reflectance near the sediments with one vs the other sensor?

    Again, in the 50 cm columns with sediment:
    at sediment bottom(6cm above sediment): 55: 57

    So this answers the sensor differences. In some cases the Apogee had higher readings, some lower, but neither varied much. I think some like to discuss issues with the sphere based on water column issues with corals in deeper systems, with plants, it's generally not an issue from what I've seen and measured.

    The Apogee is a new meter and calibrated, so is the 193 LiCOR. I do not think that argument in differences is going to hold up. The results I just did in paired test comparisons simply do not support the differences speculated. There was very little error and differences between the meters.

    As far as the differences in the reflectors, I think swapping ballast is a good idea, or measuring the ADA HQI part, or even removing a reflector and adding to another hood to see and measure differences. I'm not sure if I'll be able to do that at AF. I'll see if Steve says okay or not.

    All that is really left is the ballast and reflectors.
    I will really need to see some extremely strong arguments to suggest, under these conditions, that there was a large degree of difference between the PAR reading sensors I measured using the Apogee at AF.

    One item scratched off the list.
    Ballast and reflectors are next.
    I can also measure the reflector size(bulbs are the same fortunately) and depth etc, and look at the pattern, take a pic of each.

    However, while this might be a little debatable for the point sources like HQI only, what about the same readings with the PC set ups as well?
    How can those be explained away?

    I'm pretty sure about the general readings and the initial results.
    They have stood up and I've tested them a few times, so did George at AF.

    The comparisons between the meter sensors where as good as another LiCOR with the 193 sensor, so I have little reason to question the Apogee's readings at AF.

    While we can heap speculatory critique till the cows come home, I need some results/methods that convince me otherwise and some real work in the situation we are discussing before I change my mind. I am/was willing to go back to make sure. Maybe I missed something the first time or two or did not comopare the sphere sensor vs the flat. Well, I did. I am certainly not convinced and much less so now and can support it.

    I'll check the reflector and ballast issue out later on next week.


    Regards,
    Tom Barr
     
  20. Tom Barr

    Tom Barr Founder
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    Well, since Sanjay, a reefer who's written and fair amount on the topic about light(I searched him the other day and what do you know? He's right here at UC Davis too), happens to live here in Davis, exactly where I am also at, I could simply go discuss it and show him directly then?

    Sanjay Joshi

    He's an engineering guy, I'm a botany guy, we are both hobbyists.
    Also, if he wanted to, he could go to SF and see the tanks in question himself.
    As well as see about the sensors.

    So I can stop by and say Hi when I'm over at campus later this week in Robbins Hall:cool:

    Regards,
    Tom Barr
     
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