Lighting Question

[neon]

I have a 55gal tank. With a sand bottom and two power filters. My light is a T5 4bulb. I have 2 reef with 10,000K and 2 reef blue actinic's are these good for growing plants? Or do I need to change my bulbs to slimPaq 6700k. What are some good plants that grow well in discus tank?:confused:

[underwaterforest]

Hate to say it but those bulbs aren't the best for growing plants. The 10,000k ones could be usable in a pinch (not great), but the actinic bulbs are completely worthless for good plant growth. ~6,500K are great (blue) bulbs for general plant growth and is what I use. Lower kelvin bulbs such as 3,000-4,000k (red) bulbs can be used to stimulate flowing but again usually worthless for a plant tank unless mixed them with blue bulbs for a full spectrum effect. I'd say get the 6,700 one you are looking at if you want to have a nice planted tank setup with good growth. Most plants love an acidic tank, my planted tanks (non discus) get to nearly 5.0 pH sometimes when I am trying to have fast plant growth due to the Co2 injection.

[zamboniMan]

I have a 55gal tank. With a sand bottom and two power filters. My light is a T5 4bulb. I have 2 reef with 10,000K and 2 reef blue actinic's are these good for growing plants? Or do I need to change my bulbs to slimPaq 6700k. What are some good plants that grow well in discus tank?:confused:

I wouldn't worry about the 10,000K bulb. I would swap out the actinics for some 6700k daylight bulb.

[Fraise]

I wouldn't worry about the 10,000K bulb. I would swap out the actinics for some 6700k daylight bulb.
i second that. i used to have the same lighting on my 40G and the plants grew great. i now have 6700k CF's and i really like the colour rendition they provide.

[underwaterforest]

Fraise and zamboniMan are correct you can certinally use the 10,000k bulbs. I just really like the extremely fast plant growth which my blue bulbs deliver, and the color rendition is nice to my eyes. But then again I might be a little overboard on the lighting side of life, heck my 36 gallon plant tank has 165 watt of t5/cf of light (mmm 4.58 wpg!!). That is why I don't have discus in that aquarium they might go blind literally. I tried an experiment with a 15 gallon tank with 100 watts (6.66wpg) but I think I fianlly found my upper limit on light, but the plants must have grown 2 inches or more daily. I just ended up just using two bulbs out of the 4 on my fixture and everything looked great.

[bs6749]

I agree that you should keep the 10K bulbs. You could keep the actinics or you could swap them. By keeping them your plants aren't going to benefit, however you don't necessarily need high lighting for most plants. Some plants that grow well in a discus tank would be anubias, which like to be tied to things like driftwood. If you go that route then the two 10K bulbs would be sufficient for growing anubias, which are undemanding plants. Keep the actinics if your fixture needs 4 bulbs in it to function or if you like the look of them, if not you can always ditch them. If you go out and replace the bulbs you can end up with too much useable light over the tank and you will see algae, which you will want to avoid. I say just do the two 10K with the actinics for now and go from there. That way you aren't out any money or time.


But then again I might be a little overboard on the lighting side of life, heck my 36 gallon plant tank has 165 watt of t5/cf of light (mmm 4.58 wpg!!).

True, you might have that many watts per gallon, but it tells you very little about the quality of lighting over the tank. Watts mean absolutely nothing to plants as a watt is a unit of power (joule per second). All it tells YOU is how much it is going to cost you to power the fixture. What matters to plants is lumens, temperature/color/spectrum, and how long the lights are on. T5 bulbs are about 1.75 times as efficient (if I remember correctly) as the normal output (NO)/T12 bulbs on which the "wpg rule" was based. That is, for the same amount of energy used per socond (power) a T5 fixture will be able to output about 1.75 more lumens than a T12 bulb. Power compact/compact fluorescent bulbs are about 1.35 times as efficient as a T12 bulb. You can only use the "wpg rule" if you are comparing bulbs with the same spectrum, and wattage and of the same style unless you use the efficiency multipliers. You actually have far more than 5 "wpg equivalent" over your tank.

[underwaterforest]

bs6749 is right about the algae with a high light aquarium, it can get out of control fast especially on a newly setup tank. The only way that I can get away with the extremely high light outputs on my tanks is with use of a UV sterilizer. With the UV hooked up I have crystal clear water, and I don't have to run it all the time, just when I need to clean up the water. Lumens are a more correct way to state light output but I didn't want to look up the specs, and I can easily divide gallons by watts for a relative measurement. Another tip is usually run your light for only 12 hours or less a day. Since after 12 hours the peak efficiency of your plant's photosynthesis starts to go down and the algae (bad) take over. Of course I learned all theses lesson the hard way. :) Another tip, don't waste your money on expensive "aquarium" bulbs at the pet shop, you can get the same or better in horticultural lighting for half or less the price (a T5 is a T5 as long as the watts are correct).

[bs6749]

Lumens are a more correct way to state light output but I didn't want to look up the specs, and I can easily divide gallons by watts for a relative measurement.

I'm not trying to sound like a smart ***, but watts can't tell you how many lumens (intensity of light) are being output as the efficiencies between bulb types are very different. That's why you can literally hold your hand around one of the spiral CF style replacement bulbs in your house. They put more energy into production of light than heat. Try doing that with a standard incandescent bulb for 10 seconds after it's been on for 10 minutes...I dare you.

I will say that if you were comparing a T12 bulb to another T12 bulb of the same spectrum but higher wattage, then YES, you would be relatively confident that the higher wattage bulb puts out more lumens. The reason for this is that efficiencies of certain bulb types aren't going to increase that much and are the same between bulbs of the same style. If a 100W T12 bulb puts out 1000 lumens then a 200W T12 bulb of the same specturm should put out somewhere around 2000 lumens give or take. You shouldn't expect something like 4000 lumens out of a 200W T12 bulb if the 100W T12 is known to put out 1000 lumens. All these numbers were made up and could be very far from actual numbers, just trying to make a point.

If you are comparing different types of bulbs you must use multipliers. I can tell you how many dogs I have per gallon too, but what good does that do? Are they little toy poodles that will eat 1 cup of food per day or are they large 250lb mastiffs that will eat 6-8 times as much or more? Get my point? Though they are both lights, they are pretty different.

[underwaterforest]

To me I really don't care too much about the specs, other than I want the most bang for my buck. And I get that with t5 horticultural lighting since it is one of the most efficent lumens per watt technologies out there (other than LED of course). In the end it just comes down to two things, do I spend the least money on power for good lighting meaning, high efficiency and secondly do I get good plant growth. I get both results with with T5's and CF bulbs at 6,500k. Why I choose 6,500k bulbs is due to the maximizing chlorophyll activation energy which is what green plants love, and there are lots of plant bulbs using this spectrum.

[scottishbloke]

I agree, the watts per gallon rule does not really apply unless you are using the older, inefficient T-12 bulbs, and the 10,000k bulbs and actinics are much better for reef tanks, but not for planted tanks. In my own experience, 6700k bulbs are by far the best for planted tanks and they make everything look good. I've been using the Hagen Glo 54w T5 HO bulbs for years in my 55g plant-growing tank and also in my new 90g discus tank (which is a BB with a large driftwood feature and attached Anubias, and Floating Water Sprite which multiplies very quickly). The bulbs are 6700k, have large output spikes in the red, yellow-green and blue parts of the spectrum, and each put out 4,300 lumens (around 79 per watt, very high efficiency). Right now the two Pygmy Chain Sword plants I put in my 55g (which I'm growing specifically to trade to my LFS for a $300 Eheim Pro 3 2075 canister) are each sprouting around 4 new plants every week under just ONE of these bulbs, with NO CO2 or regular ferts, just Fluorite, Rainbowfish poop, and 50% weekly w/c. I should have enough plants to make the trade in another 3 months at that rate of growth, not including the 20 or so Red Tiger Lilies and assorted other plants in there I could also sell. Indeed, I also got my first 4 Stendker discus by trading bagfuls of plants and some Rainbows for them. There are many others on this forum that are planted tank experts and can give you excellent advice whatever route you choose to take, whether hi-tech with CO2 or low-tech, but I'm sure they will agree, 6500k bulbs or similar are the ones to use.

My $0.02

Colin