Need your advice on purchasing a light for my soon-to-be high light tank

Henri

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Hi everyone! I hope you're doing well.
I am seeking everyone's adivce on purchasing a new light for my 20 gallon tank, it's a bit taller than longer, bu you can call it a 20 tall. I am really unexperienced on purchasing lights, so here's where your help is needed. What kind of bulb do I need for this tank to make it a high light tank? I'm planning to densely plant it. I'm not sure what bulbs the store has, T5 or T8, T10, T12 etc etc. but do I need to follow to rule of 3+ watt per gallon needed to make a high light tank? Is it true? It might be tough to find a 60watt in my area, so eg does a 30 watt bulb make it a high light or a moderate? I know that i depends on the bulb, but...
Also my light fixture is done by the previous owner of the tank and he only siliconed a bulb slot to the fixture. I'm planning to add more, but i wanted to know if is there a minimum distance between each bulb, will the over heat each other until they crack/burn?
Thanks again for your answers!
P.S. Sorry for any possible mistakes, I'm on my iPod and it's 1AM here lol...
 

bass master

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Hi Henri,

The T5, T8, T10 refers to the diameter of the fluorescent tube. The number after the "T" is the diameter in 1/8th inch increments so a T5 bulb would be 5/8th of an inch in diameter, T8 would be 1 inch in diameter, etc. T5's have the lowest diameter and the best lumen output per watt; a 20 watt T5 bulb would put out more light than a 20w T12 bulb which generally makes T5 fixtures best if you can get enough wattage out of them. Larger bulbs will give you more watts for their length, however. An 18" T12 bulb would carry more wattage than an 18" T5 bulb. Your ideal light would be a T5 fixture with around 60 watts but this might be hard to do if you're limited in your selection.

T5HO (T5 high output) are ideal if you can find them as they use advanced ballasts to power brighter lights while still using smaller bulbs. If you're still not able to find anything that suites your needs you might want to take a look at CFL fixtures, there are a few threads about this on these forums.

Another thing you'll certainly want to consider when picking out your lights is the Kelvin rating of the bulbs you buy. Bulbs with a Kelvin rating 5000-10000K work well for planted tanks with 6500K being ideal.

60w of lighting would definitely put you on the high-light side of things while 30w would put you on the lower end of moderate lighting (in my opinion at least). This does vary a little depending on what type of lights you use, tank height, how effective your hood is at directing light, and a number of other factors. I have a 20 tall as well with 55w of lighting and consider my tank to be on the upper side of "moderate" in lighting because I used 1 T8 bulb and 2 T10 bulbs, giving me a fair bit less lighting than if I had 55w of T5 lighting. You'll want to get as many watts as you can if you're trying to care for plants with a higher light requirement, but you'll also have to do some experimentation yourself to see what plants will and won't work under your lighting, it's not quite an exact science unfortunately.

I'm not too experienced as far as the spacing between bulbs, but if I had to guess I'd give at least half the bulb's diameter in spacing i.e. 1/2 inch spacing if using T8, 5/16 inch spacing if using T5, etc. That seems to be roughly what I see in most manufactured fixtures. As long as you ventilate your hood well enough you probably won't have to worry about the bulbs overheating each other, but they'll need some space to allow light to reflect downward in between the bulbs.

Good luck with your project
-Bass master
 
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Henri

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Hi Henri,

The T5, T8, T10 refers to the diameter of the fluorescent tube. The number after the "T" is the diameter in 1/8th inch increments so a T5 bulb would be 5/8th of an inch in diameter, T8 would be 1 inch in diameter, etc. T5's have the lowest diameter and the best lumen output per watt; a 20 watt T5 bulb would put out more light than a 20w T12 bulb which generally makes T5 fixtures best if you can get enough wattage out of them. Larger bulbs will give you more watts for their length, however. An 18" T12 bulb would carry more wattage than an 18" T5 bulb. Your ideal light would be a T5 fixture with around 60 watts but this might be hard to do if you're limited in your selection.

T5HO (T5 high output) are ideal if you can find them as they use advanced ballasts to power brighter lights while still using smaller bulbs. If you're still not able to find anything that suites your needs you might want to take a look at CFL fixtures, there are a few threads about this on these forums.

Another thing you'll certainly want to consider when picking out your lights is the Kelvin rating of the bulbs you buy. Bulbs with a Kelvin rating 5000-10000K work well for planted tanks with 6500K being ideal.

60w of lighting would definitely put you on the high-light side of things while 30w would put you on the lower end of moderate lighting (in my opinion at least). This does vary a little depending on what type of lights you use, tank height, how effective your hood is at directing light, and a number of other factors. I have a 20 tall as well with 55w of lighting and consider my tank to be on the upper side of "moderate" in lighting because I used 1 T8 bulb and 2 T10 bulbs, giving me a fair bit less lighting than if I had 55w of T5 lighting. You'll want to get as many watts as you can if you're trying to care for plants with a higher light requirement, but you'll also have to do some experimentation yourself to see what plants will and won't work under your lighting, it's not quite an exact science unfortunately.

I'm not too experienced as far as the spacing between bulbs, but if I had to guess I'd give at least half the bulb's diameter in spacing i.e. 1/2 inch spacing if using T8, 5/16 inch spacing if using T5, etc. That seems to be roughly what I see in most manufactured fixtures. As long as you ventilate your hood well enough you probably won't have to worry about the bulbs overheating each other, but they'll need some space to allow light to reflect downward in between the bulbs.

Good luck with your project
-Bass master
Hi Bass master, thanks for your reply.
Appearantly, I have a T8 bulb. The only reason why I want new lights is that the current bulb produces green light and it wont help me with my plants. I am familiar with the K degree of the lights, but in contrary to my 10 gallon's light, this green bulb doesn't have the Kelvin rating on it.
I went to the LFS and asked for lights and the man there told me that the prices of lightbulbs are from $8 to $12. I went to the hardware store and they actually had bulbs, I showed them my green T8 and they told me they had lights of the same dimensions, only that these lights are standart ones and every bulb has the same wattage as my bulb's 18watt. Am I better to go if I buy the light from the hardware store? It costed only $2. It will save me a lot.
My hood is not ventilated, I got it from another guy and I think it's a DIY... What can I do about this? How do you ventilate your hood?
Finally, I really think CFLs will help me with my problem, I can get many of them, but how do I put a CfL bulb in my light fixture? Take a look at it:
 

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bass master

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Bulbs designed specifically for growing plants are slightly more effective per watt as they have multiple phosphors to give a more complete spectrum of light, although bulbs from the hardware store will get the job done just fine.

Slicing some slits in the top or back of your hood will let some air flow through to ventilate it. This isn't entirely necessary so don't worry about it too much, but if you're going to build your own hood its just something you'll want to factor into your design.

As far as fitting CFL's into your hood, its an easy enough conversion. Most hardware stores will have an adapter that will convert an A/C outlet into a lightbulb socket. Buy a few extension cords and a few of these adapters and you should be able to rig it all together into a CFL hood. Here's an example about what I'm talking about:


This guy wired in his own sockets, which might wind up being cheaper, but I think it illustrates what I'm trying to say

-Bass master
 
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Henri

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Bulbs designed specifically for growing plants are slightly more effective per watt as they have multiple phosphors to give a more complete spectrum of light, although bulbs from the hardware store will get the job done just fine.

Slicing some slits in the top or back of your hood will let some air flow through to ventilate it. This isn't entirely necessary so don't worry about it too much, but if you're going to build your own hood its just something you'll want to factor into your design.

As far as fitting CFL's into your hood, its an easy enough conversion. Most hardware stores will have an adapter that will convert an A/C outlet into a lightbulb socket. Buy a few extension cords and a few of these adapters and you should be able to rig it all together into a CFL hood. Here's an example about what I'm talking about:


This guy wired in his own sockets, which might wind up being cheaper, but I think it illustrates what I'm trying to say

-Bass master
Oh, I thought you would put some kind of tiny fan in the hood lol.
CFL's would be a way better option, I would be able to put many more for my tank. A problem is that my light fixture is only 4,4" from front to back. So I think that putting the CFL in the same position as the guy in the thread you linked will, they wont fit in my hood. Can I put them vertically instead, just like we put them in our household socket and outlets?
And then I assume I'd have to drill the holes on the top of the hood?
I also have no idea how to connect all the bulbs together with only one plug...
Thanks for your help so far!
 

bass master

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Yep, vertical will work fine too. There are a number of ways to wire them all together, an electrician at your local hardware store can probably demonstrate better than I can over the internet.
 
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Henri

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Yep, vertical will work fine too. There are a number of ways to wire them all together, an electrician at your local hardware store can probably demonstrate better than I can over the internet.
You're more than right. I'd propably buy a single high wattage cfl, a 60/70 watt if I find one of these, so it will be easier than buying several ones and wiring them together.
Oh, one more last question that I have, what is this. The thing you will see in the attached pictures? Is it the adapter you were talking about? It was in the hood. Do I have to replace it for each bulb? Do I need it at all with CFL bulbs or is it just for the large compact fluorescent bulbs? Im really confused and don't know what to do with this one... Feel free to ask any question about it so I can help you help me explain me what it is (LOL).
 

bass master

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I believe that is the ballast+starter for your current fluorescent tube fixture. CFL bulbs have these provided and need nothing more than to be screwed into a standard light bulb socket.

I've personally never seen a CFL bulb over 23 watts, but if you can find something higher I'm sure it would be usable. Also keep in mind though that having multiple smaller lights will provide light much more evenly across your tank. Having your light too centralized can cause some problems for your plants, best to keep it even.

-Bass master
 
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Henri

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I believe that is the ballast+starter for your current fluorescent tube fixture. CFL bulbs have these provided and need nothing more than to be screwed into a standard light bulb socket.

I've personally never seen a CFL bulb over 23 watts, but if you can find something higher I'm sure it would be usable. Also keep in mind though that having multiple smaller lights will provide light much more evenly across your tank. Having your light too centralized can cause some problems for your plants, best to keep it even.

-Bass master
Oh that's great! I thought it was something that every light bulb needed... I'm good to go then!
Seriously, you've never seen CFLs over 24 watt? What about those used at home for example? The other day I saw 55watt CFL bulbs at the LFS. But I think one of thise wont be enough for my 20gal.
Thanks a lot for your help!
 
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