What type of lighting should I buy?

[mandy2936]

Hello,
A little while back I started a thread about lighting for my 20g. I wanted to upgrade my standard lighting that came with the tank to lighting that is strong enough for plants.

On here I was informed about K ratings, so I headed out the pet store to pick out some lighting. I guess the store employee was wrong. (No surprise there... I should have known better.)
I asked him which lighting would be better, as one said it was suitable for plants and brings out the fish's color, (We'll call it light A) the other said just for plants. (Light B) He told me that either would be fine, but light A would be much stronger than light B.

So, I went with light A, thinking that it would be good because it bring's out the fish's colors. Light A was 18000K, and light B was 10,000. I thought that what he said about light A being stronger made sense, because 18,000 is more than 10,000, right?

Well, when I got home, I found out that the k rating system works backwards... meaning that 6500k is stronger than 10,000k, right? Well, that's what confused me, because on here I was advised to look for lighting that was at least 6,500k , so I had thought that 18,000k would be even better.

So basically, the lighting really does bring out the fish's color fantastically, but I still want to be able to have live plants.

So, could you help a plant newbie out here, and tell me what exactly I need to buy when I head out to the pet store today? I want to get it right this time. Thanks!

P.S, What I said about the K ratings working backwards was really just my guess.. that's the only way I can make sense of a 6,500k bulb being stronger than an 18,000k bulb.

Thanks again for your patience!

 

[BigJim]

The Kelvin color temperature isn't a measure of strength of the light, it's a measure of the light color. Low numbers are more towards the red end of the spectrum, high numbers towards the blue end.

Wattage is a much more important metric to consider. You can get a 10W bulb in 2300K, 6500K, or 10000K, but none of them would grow many plants in your 20g. 30W of 6500K fluorescent light would be good for med-low to medium light on your 20g. Aim for that.

Light is a very complicated entity. The metrics that best quantify the characteristics of light are difficult for the average person to measure. As a result, we attempt to make rules of thumb.

 

[neilanh]

Bigjim nailed it. K value and wattage are 2 different aspects that have to be considered in planted tanks.

Plants like yellower light (5000K) range and do well in the 5000 to 10000K range. Above that the amount of usable light for the plants starts to dimish because the color of the light isn't efficient for them to photosynthesize.

Once you have the color, you need to determine how much light, in watts, you need. This is based upon what kind of plants you want to keep.

 

[mandy2936]

Thank you both for the replies!
I would like to have some crypts... And possibly an anubias nana... Basically some good beginner plants.

So, how much wattage would I need? I currently have the 18000k light in there. It's a single 18" flourescent tube, 15W, and has T8 written on there?

Anyway, thanks again! I'm about to head out soon.

 

[BigJim]

18000K is a bit much. A good plant bulb will be in the 6700K range. Unfortunately you can't change the output of a fluorescent fixture just by changing the bulb. You're stuck with a 15W bulb because of the ballast.

 

[mandy2936]

Huh? So I would need a whole new hood in order to get good lighting?
So confused...

 

[neilanh]

Ok, so what he was saying basically is this.

On any light fixture, you can buy different bulbs to change the K value (color) of the bulb.

However, you can't change the wattage of the bulb without changing the unit that powers the bulb inside the fixture.

What that means is, to host plants in your 20g tank you really should have a little bit more light than you currently do, so you should consider buying a new light fixture, (or adding a second fixture to the one you already have).

You can give it a try with the fixture you have by just replacing the bulb with a different (more plant friendly) color, but it's still has to be a 15W T8 bulb.

 

[mfdrookie516]

Basically. You can probably get away with anubias, java moss, and java fern, but they'll grow very slowly. Is a 20g 24" wide? If so, you can get a 2x24w T5HO fixture relatively cheap... And you can do 1 6700k bulb and one actinic to keep it simple, low light, no co2... or you could do 2 6700k bulbs, do co2, and keep a nice variety of plants.

 

[mandy2936]

Well, I might be able to get a new light fixture, but that depends on the cost. As a kid, I'm on a tight budget here. I just thought that live plants would be a great addition to my tank, with all their benefits. I had no idea it would be more complicated than just switching the bulb. (Shows how little I know...)

First off, what would I even be looking for, "fixture" wise?
Second, for low-lights like Anubias and Crypts, what is the wattage that I need?

Thanks guys.

 

[BigJim]

The T5HO fixture mfd recommended would be great. You could run the suggested actinic bulb to cut output down below where you need to inject CO2, but you'd have the potential for an easy upgrade if you want to get more serious about plants in the future.

If you can find a hood with incandescent sockets, CFL bulbs offer the best bang for your buck. I run daylight spectrum CFLs from the hardware store over two of my planted tanks. You can DIY a CFL hood pretty easily too.

Aim for 1-1.5 Wpg for low-light plants. The plants will grow better closer to the 1.5 Wpg mark. I've got two 18W CFLs over my 29g and I can grow java fern, anacharis, and anubias pretty well.

 

[mfdrookie516]

You can get a 2x24w fixture for $65 + shipping ($10 i believe). fishneedit.com is the place to get them. I have one fixture from there already and just ordered 2 more that should be here in the next couple days.

 

[neilanh]

I think that's way too much light for the OP. My recommendation here is to try to get something in 20-30W range and no more light than that.

 

[mfdrookie516]

Running one 6700k and one actinic for now? My thought was that now she can try it out with one bulb, then if she decides to go all out and go high tech, all she'll need to do is replace the bulb.

 

[mandy2936]

Thanks everyone for your replies and input!

Is it official that I will need a new fixture for live plants? Just making sure.

I don't plan to upgrade to high tech in the future, as I really only want somesort of live plant in my tank for the benefits.
I don't mind fertilizing, but I would like to stead clear from CO2. Low-tech is the key for me... I'm very into my fish, but the technical parts go right over my head. Lol.

At this point I'm still a little confused... but you guys are doing a great job of keeping your patience with me!

 

[mfdrookie516]

Is it official that I will need a new fixture for live plants? Just making sure.

Pretty much unless you want to limit yourself to anubias and java fern... but even those two would grow very slowly under your current fixture IMO.

I don't plan to upgrade to high tech in the future, as I really only want some sort of live plants in my tank for their benefits.
I don't mind fertilizing, but I would like to stead clear from CO2. Low-tech is the key for me... I'm very into my fish, but the technical parts goes right over my head. Lol.

I used to be the same way. I couldn't understand why anybody would go through the cost and trouble of the expensive fixtures, the pressurized co2, etc... I fell in to the trap and COMPLETELY understand why now

 

[BigJim]

At this point I'm still a little confused... but you guys are doing a great job of keeping your patience with me!

We're here to clear up confusion. Ask away.

I used to be the same way. I couldn't understand why anybody would go through the cost and trouble of the expensive fixtures, the pressurized co2, etc... I fell in to the trap and COMPLETELY understand why now

It's a slippery slope. I started the slide maybe 12-18 months ago and it's quickly becoming a free fall. The challenge of trying a high-tech planted tank on the cheap (relatively) was too much for me to resist.

 

[mandy2936]

We're here to clear up confusion. Ask away.

Thanks! The people on AA are just so darn helpful

Pretty much unless you want to limit yourself to anubias and java fern... but even those two would grow very slowly under your current fixture IMO.

OK so ummm what do you mean? Are you saying that the current bulb I have now, 15w 18,000k, can support Anubias, or are you saying that a new bulb in the current fixture that I have now would support Anubias?

Also, two more questions.
If you meant that to support Anubias/Java Fern I can keep my fixture but swap the bulb, then whats the K rating/wattage I need?
And finally, if I get a new bulb, but don't get a new fixture, can I just change the fixture in the future, or would I need a new bulb again??????

 

[mandy2936]

Ok I'm going to the pet store again soon... so help is appreciated. If it's not too costly, I might get that new fixture, too!

Sent from my iPod touch using the AA app

 

[meegosh]

You are going to want a 6500k bulb or as close to it as you can. If you decide to upgrade your fixture later on down the road that is fine - it will come with its own bulb. No need to worry about buying new bulbs (unless the fixture doesn't come with 6500k bulbs)!

I just picked up a 18" 15w T8 bulb for my 20g high at petco. I got the Sun Max bulb which is 6700k. They had Flouramax bulb for planted tanks but it was only 5500k. I opted for the 6700k because that it was I had in my 10g (I upgraded to a 20 high) and in my 30g long - Both of which were doing great.

 

[mandy2936]

Thanks! I will look at some fixtures, so basically all I need is one that comes with a bulb close to 6500k and is the same dimensions as my current one? Would just buying a bulb be a waste if I don't have the proper fixture to support it?

I just got off the phone with a Petsmart employee, asking if I could return my 18,000k bulb, even if I've used it for a few weeks. All I needed was a yes or no, but then she started really confusing me on the type of bulb I would need. Sooo I'm just gonna stick with the advise on here, I find it more reliable!
Thanks guys