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BradSD 09-29-2010 10:52 PM

New Light Fixture
Was shopping for a new light fixture today and the only bulbs I could find with the fixtures are the 10,000k or more. Why no lights with 6500k? Will the high k hurt my plant growth? These were T5 HO light fixtures.

1077 09-30-2010 03:53 AM


Originally Posted by BradSD (Post 482414)
Was shopping for a new light fixture today and the only bulbs I could find with the fixtures are the 10,000k or more. Why no lights with 6500k? Will the high k hurt my plant growth? These were T5 HO light fixtures.

I would submit and I believe Byron would agree that T5HO over your 55 gallon without CO2 injection or daily EXCEL (liquid carbon source), that you will soon have a tank full of beautiful and various forms of algae.
The T5 bulbs would represent High lighting and thus CO2 would be the limiting factor with regards to plant growth.
With high light and limited CO2 as well as limited nutrients, algae are much quicker to respond to these conditions than plants are.
I would were it me,(and it ain't) look for twin tube fixture that accepts T8 bulbs in the 6500Kto 6700K range.
These bulbs are much easier to find at places like LOWES and would be better suited for NON CO2 planted tanks.
When you increase the lighting over a tank with plants,you must also increase the nutrients which are more in demand, but more nutrients without CO2 also in higher demand,, then the plants will do poorly, and algae will thrive.
I recently set up a low tech ,low light, 80 gal planted tank with help from Byron and others ,and the tank is lit with 2x32 watt 6500k T8 bulbs and and once weekly dose of dry fertilizers along with Flourish comprehensive.
Plants are plants suited for low to medium or moderate light and growth is slow but steady.
CO2 and light are the driving factors in plant growth followed by nutrients available. One cannot increase one without the others and still achieve the balance needed to encourage plant growth and discourage algae.
I tried against all advice to the contrary ,to run 2x54 watt T5HO bulbs which produce considerably more light than T8's but were well within the often mentioned 1.5 to 2 watts per gallon for low tech tanks and the results were ...Plants faltered. there was not enough CO2 or nutrients to provide for the increased demand by the plants due to faster uptake rate that higher lighting presented.
I did begin to grow various forms of algae which pretty much was exactly what others said would happen but being somewhat bullheaded,,I had to see for myself. Seems I always learn the important things or the tings that stick with me,, the hard way.
Byron could prolly explain more in detail what I have attempted to, but I would hate to see you buy an expensive fixture and receive poor results. Hope some of this helps, I am still learning about the planted tank realm myself . And thus far,, I have learned that it is as difficult as I choose to make it.:roll:

BradSD 09-30-2010 07:35 AM

Thanks for the information. Actually my tank is doing very well with my old light fixture and 64 watts of 6500k lighting. The main reason I want another light is for its features such as the legs to raise it above the lid, moonlighting for night viewing and seaperate cords for running timers. Truthfully my lighting is perfect on my existing setup which is actually two standard light fixtures. I just hate how they block my lid and look ugly on top of such a pretty tank. One thing I do not want to do is harm the success I have had with my tank ( thanks to help from Byron and company here). I will have to come up with a solution of some sort. I have no plans to go high tech, I have no interest in the expense and headach of all that. Thank you for the information.

Byron 09-30-2010 11:35 AM

1077 is on the mark. I don't know what fixture you have, but if the appearance is annoying, a new fixture may be OK provided it is T8.

I use All Glass fixtures, with my own tubes (the "plant" tubes they come with are garbage and immediately go to recycling). I bought two of these last year to replace old fixtures in which the ballasts went after 12+ years. These sit across the tank frame so there is no light above the tank (which is very distracting for viewing, and less light reaches the plants the further the fixture is above the water). I have glass covers that sit down inside and on the lip of the frame out of sight. You might see the look in my photos. The fixture cord plugs into the timer which is plugged into the wall outlet, or it can be in a power bar.

T5 HO light is very bright. When my first old fixture went, I bought one of these, it had two 48-inch tubes the same as my T8 over the 115g five-foot tank, and I bought 6700K Life-Glo 2 full spectrum tubes, same as I had been using except T5 HO. The intensity of light is 1.5 more with a T5 HO than a T8, comparing the same type and spectrum, in this case a Life-Glo 2 type, 6700K. So 2 T5 HO tubes is more than 3 T8 tubes in intensity. And it was obvious. I kidded that my fish would be asking me for sunglasses. It was far too bright, and that was over a 5-foot 2-foot deep tank. I used it for a week to give it a fair try, then returned it for the T8 All Glass.

As for the 10000K tubes, these are intended for marine tanks that need high blue light (the higher the Kelvin number the more blue and less red). While opinions vary, the majority of planted tank folks will not recommend actinic or high-blue light, and I have so far not read any of the true authorities who do. In a mix, it can work; studies have shown that a combination of full spectrum (6500K) and cool blue result in the best plant growth response. I have such a combo over my dual-tube tanks, one is full spectrum 6700K (a Life-Glo 2 currently) and the second is a cool white that varies from 7000K to 11,000K. I like the slightly "cooler" look than going with a "warmer" look which I would get by having a second tube say 5000K. I have done this, just didn't like the look. Once has to first consider plants, then appearance to us/you. Within a certain range, plants do well, so it then becomes a matter of your preference. But you can't loose with 6500K balanced.

Last comment on moonlights; OK so long as they are not on all night. Fish and plants need complete and total darkness for around 10 hours nightly.


BradSD 09-30-2010 12:18 PM

Again,,,,,,thanks for the fantastic info!

Angel079 10-02-2010 10:04 AM

I can only underline what's already been posted, if you want to go the route of higher end lights you need to adjust your nutrition level as well to avoid further issues.

I'd shop around to either find a kit to raise what you have or search the DIY section for ideas. Good looking and perfectly great working (for the plants & fish) lights do not have to be expensive nor require you to go for a entire high end set up all around, there's many DIY ideas to make it look very nice and elevated with existing fixtures (Example I use normal shop lights with GE bulbs @ 6500K from Lowes with DIY wood casings stained to match the stands).

redchigh 10-02-2010 10:21 AM

Instead of a new fixture, you can build a wooden frame to go around the light (wood is pretty cheap- 1/4" thick boards could be stained with a wood stain to match your aquarium stand, and theoretically just be epoxied to the light fixture.

A full canopy would probably look nicer (build the canopy to be the same size as the edge of the stand below, or about 1/2" wider and longer than the aquarium on all sides, with the front panel on a hinge to feed the fish and adjust the lights.) but that would probably take a teeny bit more work.

As for the lunar lights... I don't buy into it. Can fish not see the color blue or something? Don't the blue lights bother them a bit?

Angel079 10-02-2010 05:52 PM

That reminds me of the action for the 55g last year...if you look at this link New 55g - 55 gallon Freshwater fish tank the 3rd picture you'll see the stand and hood to house the lights I build for the 55g and I like it quite well to be honest, now don't quote me a 100% cause its been a while but cost for the stand, lights & wood hood was somewhere around the house number for $60-70

BradSD 10-03-2010 07:09 AM

That turned out nice Angel esp for the dollar amount spent. Im sure the bow in the front of mine would cause a bit of dificulty but there is bound to be a way. I do have a 2nd aquarium that I could do this with easier. Its a standard 50 gallon Cichlid tank.
I have eyeballed my local Lowes shop lights. For a mere 14 bucks you can get a double light but no switches and its a bit ugly. I thought maybe I could suspend it from the ceiling with something nice, leaving it about 2 inches above the tank. Just something I have kicked around, they do come in black which would be nice should I decide not to have a canopy.
As far as the moonlighting I do think it could replicate the natural enviroment somewhat. I have spent time out on the lake at night fishing and on a full moon there is a lot of natural light out there. The only total darkness would be cave fish or very deep water fish. Plus its a neat feature I think but to each his own.
Byron mentioned the light being raised above the tank would be a distraction and I never thought of that but its a really good point. I was hoping to get my lights off the lid to have access to the top of the tank. Its a bit of aggrevation to have to move a fixture or even sit it in the floor to change water or feed the fish. I could see how light bleeding out of the top would be a huge negitive so point well taken. I will keep this in mind!
Thanks for all the thoughts and tips! Seems a fish hobby company would build us planted aquarium hobbiest a light fixture that would work for us, guess not at this time.

Byron 10-03-2010 05:39 PM

I have twin-tube fixtures on my large tanks and I don't usually move them for water changes. The glass covers I do remove to clean, as they will become "cloudy" over time from the condensed water being heated by the lights and then even less light gets through. But the fixture sits over the latter half of the tank and sometimes I may push it further back if I need to work on the water surface or something.

On the moonlights, as long as there is still a substantial period of complete darkness, say 10 hours, fine. Most of our fish come from forest streams that rarely if ever see direct sun or moon. They have 10 hours of daylight and 10 hours of complete darkness-pitch black; the other 4 hours are obviously dusk and dawn. Even in the mid-day, the water is so overgrown by the forest the fishermen need flashlights to see the fish. I've posted a couple of videos on natural habitats of angels and cardinals a while back that demonstrated this; underwater they were filming with searchlights, yet on the surface it was bright day. I don't know the extent to which fish will be affected by lack of sufficient darkness, but they are certainly not meant to have it in the tropics. And some writers mention that plants can be affected too. Not so much by the moonlight but by the lack of complete darkness.

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