Light Help

[guns286]

As you can probably tell from my other threads, this is my first try at live plants. I've been asking alot of questions and you guys have been great with the answers. I think I'm getting a good handle on what I need. But, I'm still confused about the lighting.
I have stock, "All-Glass", 48" lights. There are 2 32w florescent tubes. Does that mean it puts out 64w? Is there a watt to lumin ratio? I know that if I wanted plants with high light requirments I would need to get a whole new set up. And, I also know that my current lights would be ok for low light plants. But, if I changed the tubes in my current hood, will I be able to get medium light plants? A web site told me that my current tubes are "T8". It also said that my hood was compatable with "T8, T10, and T12" bulbs. Does this have something to do with color? Or output?
I attached a link to a website that gives a list of the other tubes that are SUPPOSED to be compatable with my hood. There is a large range on that list and I dont know what I am looking for. Any advice would be appriciated.


www.drsfostersmith.com/pic/article.cfm?aid=1372#Twin-Tube%20Strip%20Lights

 

[brutus]

Yep 64 watts on your 72 gallon very low light.You should have room to put another fixture on top and run both.T8 T10 T12 is just the circumference of the bulb.Look for a good T5HO light to add to the tank.The colour that most use are 6700K up to 10000K.If you have the plastic hood you might have to take off and get the glass top then you can add as much light as you want.

 

[guns286]

Ok. I assume that the T5 HO wont fit into my current fixture? None of those light tubes listed in the link will improve the light output? Just for monetary reasons I cant buy a new fixture right now. There were just a few medium light plants that I was looking at. Or, am I stuck with only low light plants?
Is there some way to convert my current fixture (in a relitively inexpensive way)?

 

[meegosh]

You can convert your fixture by using what they call retrofit kits. Try searching online for them in the size of your hood. They do require a bit of DIY skills and some general electrical knowledge is required (wiring).

 

[JPKeenan]

I was wondering something cause I have been looking for better lighting too.

I have seen some of the under cabinet lighting. I was wondering if rigging two of those up (minus the plastic shield on the unit) inside a hood would be any good as a stop gap until I can get the cash for a real lighting unit.

Just an idea to toss out that crossed my mind.

 

[jsoong]

If you have good DIY skills, you can rig up a decent light setup fairly inexpensively. My Dual T8 shop lights costs maybe $15. I stripped it for parts, & mounted the reflector, ballast (electronic) & endcaps inside the hood. <If you don't have a glass top, you would need to replace the endcaps with water-proof ones.> My 4 32W T8's give enough light for medium light plants.

For 4' tanks, the shop light option is the cheapest. There is really no other cheap way to improve the light output of an existing fixture. <Upgrading the fixture involve swapping out the ballast +/- endcaps, uss. costs more than a retrofit kit.> The next best would be a retro-fti kit that would fit inside your canopy. A Dual T5-HO set will run ~$100 tho.

And JP, I wouldn't mount an unmodified undercabinet fixture inside a canopy, unless you have a glass top. These are not meant to be in a wet location, and will quickly corrode & die (not to mention possible fire/shock hazard). With a glass top, you can pretty much use anything over it.

 

[jsoong]

One other thought, if your light bulbs are very old (say a year or more), you might want to try some new bulbs. I use 6700K T8 Daylight bulbs from Phillips. They are $5 or so each at Home Depot.

Older bulbs get dim over time. A set of new bulbs might just give you the cheap boost you are looking for.

 

[JPKeenan]

I'd be keeping the under cabinet lights above my lids, sort of modifying my light hood to hold two of them. I would have to check to see if the tubes I get are decent wattage and in the right K range before doing the mods.

 

[guns286]

Take a look at this link. I would'nt be buying them from this place. I found them in my local hardware store. Do you think they will be good for medium light plants? If not, I'll try the DIY idea.

electrical.hardwarestore.com/13-41-fluorescent-bulbs/ge-daylight-bulb-108548.aspx

 

[jsoong]

That would work for plants, but those are T12's & 40W. Your T8 fixture is 32W, it will not drive the 40W bulbs unless you have an over-sized electronic ballast in there. <Unlikely, and 2x40W is still low light for you!>>

There is also no advantage in using the 40W T12 compared to the 32W T8. The T8's are more efficient and put out more light per watt than the T12. <The lumen ratings on those T12's are 2700, my 32W T8's are 3000+> Anyways, the plants see a specific spectrum within the light & the last time I looked, the T8's beat the T12's hands down in producing light that the plants can use. The Phillips Advantage T8 tubes are supposed to be equal to the T-5/PC's in terms of usable light per watts.

When calculating watts per gal, one typically have to adjust the watts of the non-T12 bulbs to compensate for different efficiencies of the tubes. Typically, you increase the W's of a T8 by 20-25% to get at a T12 equivalent, and 30-35% for T5's.

 

[guns286]

Will my stock ballest run Philips Advantage T8's? And, I know that the depth of the tank is important when it comes to light strength, I just dont know how to figure it into the equasion. Its 24" deep. I'm looking to get the most bang for my buck, but I want the plants to have a healthy amount of light and florish. I would love to get a whole new fixture but I cant afford it right now. As I said before, I just want to be able to plant low and medium light plants. Thanks for the advice. Sorry if all the questions are getting annoying I just want to do this right.

 

[mfdrookie516]

yes, you can run those bulbs, because they are the same wattage and diameter. i am planning on getting some of the phillips advantage bulbs for mine too, as i dont want to break the bank on t5-ho just yet

 

[guns286]

Ok, cool. Are these lights considered "speciality" lights? Or should I be able to pick them up at the local hardware store? I tried a search online and did'nt come up with anything.

 

[mfdrookie516]

i just got one today at walmart for $4.00... in the light bulb isle... they had the daylight bulbs and also the aquarium/plant bulbs, but the daylight bulbs put out more light...

 

[jsoong]

I know that the depth of the tank is important when it comes to light strength, I just dont know how to figure it into the equasion. Its 24" deep. ...

The deeper the tank, the more light you need on top to get the same light at the bottom. A quick search reveals that you lose ~ half the light at 20'. At 2' you only lose maybe 5%. so I wouldn't worry too much about it. <After all, the low/med/high light rule is really just an approximation....>

This is a pretty good discussion at the KRIB:
Re: Light intensity and water depth

 

[guns286]

Ok, my friends, I think I might have to break down and buy a new fixture. I hope I'm not the dumbest person in the world, but this stuff is getting really confusing. It seems ALOT simpler to pony up the couple of hundred dollars and save myself a headach. From what I've read, it looks like switching over to T5 HO is the way to go. I've attached a link to the fixture I'm looking at. Tell me what you think. In keeping with the 2 watt per gallon rule, I would need 150 watts, so 216 watts will work. I also know that I should be somewhere in the 6000k range, but it does'nt tell me that. There are other bulbs that are compatable with this fixture that show the K rating. Maby I'll have to get a couple of them. Let me know what you guys think.

www.drsfostersmith.com/product/prod_display.cfm?pcatid=16771

 

[mfdrookie516]

well, there is a cheaper one... Aquarium Lighting for Freshwater and Reef Systems: Nova Extreme Compact SLR T-5 Fixtures

i was thinking about getting it, and everybody seems to like it

 

[guns286]

Thanks MF, they look PERFECT! Now, here's the question, the 48" freshwater puts out 10,000K but only 108 watts. I've heard the watts per gallon rule is outdated and that the K rating is really all that matters, but is that so?

 

[mfdrookie516]

jsoong can answer with much more experience and knowledge on this one, but from my understanding, the 10,000k rating is the spectrum of light that the bulb gives off. the watt per gallon rule is more of a general guidline, but you still need to go by it. alot of that goes by the depth of the tank, and so forth. they make 6700k, 10,000k, 14,000k, etc, but the wattage is all generally the same.

 

[jsoong]

The K is the color of the light, 10000K is much whiter than the 6700K, but both will work for plants.... just depends on how you want your tank to look. <Some people think fish look too garish in really white light .... I guess it depends on your fish & your taste.>

The intensity of the light (and its spectrum) is what determines how well your plants will grow. That is a function of the W or the bulb & its efficiency. The WPG "rule" breaks down because you have all those different bulbs with differing efficiencies, not to mention different efficiencies in reflectors, etc. If you are really into high-tech plant setup, there are websites where people have measured the spectrum of different bulbs & intensity, etc. But for the average Joe like me, I think a ballpark estimate will suffice.

At any rate, 2x54W T5HO should give you medium light in your tank, maybe a bit more if you have really good reflectors in the fixture. That 108W of T5HO will put out as much light as 160W of "normal" fluorescent tubes.