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- If I had three 42" 38w tubes on a 4' tank, which I guestimate works out at 2.85 WPG, is this a medium/ medium-high light intensity?

Can I really get tubes from the DIY store to do just as good a job as the expensive ones from the lfs..? Plain white light rather than the yellow light (which I made the mistake of buying once) I think the yellow light was called 'warm light' or something..

x

Malaikah

I personally would never buy the cheapies. The more expensive ones at you LFS as designed to do a specific job. Whereas the others are designed to omit light and that is basically it.

I have twe 4ft Sera tubes one plant light and one natural daylight. Cost $3o each and they will have to be replaced after 18 months.

Expensive but just look at my tank.

Keith

Near enough is not good enough, therefore good enough is not near enough, and only your best will do.
I VOTE DO YOU if not WHY NOT?
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Morning ladies and gentlementals.

I'm just curious, I'm looking at setting up a 48 x 14 x 18 tank, and I'm trying to figure out what I can get away with.

2 or 3 tubes?

a cheapie light bulb is not bad if its parameters compare to a more expensive aquarium bulb. alot of the aquarium bulbs are expensive because they are mated to various tank requirements. compare every aspect of an aquarium only bulb to normal bulbs. i frequently find seemingly aquarium designed bulbs at office max for $3.00 each. do some homework and save alot!

mariosim

I agree with you but, I was well informed even if they have the same output they do not last as long. Unless you have the correct measuring equipment it is impossible to know when its usefullnes is finished.


Keith

Near enough is not good enough, therefore good enough is not near enough, and only your best will do.
I VOTE DO YOU if not WHY NOT?
VOTE NOW VOTE NOW

Can anybody tell me how many WPG are considered 'high' light levels are what is considered 'medium-high'? Are we talking around 4wpg as high, and 3wpg as medium-high?

Well, in part it depends on the depth, too. A 55 needs somewhat more light than a 40 for bright-light plants near the bottom. (Back-calculating from your WPG you sound like you have a 40.) I've got 130 on a 55 and I don't think that light is the limiting factor at this point.

The general consensus is
1-2 wpg = Low
2-3 wpg = Medium
+3 wpg = high.

Personally I feel anything far above 3wpg is a bit of overkill and not really neccessary for 95% of aquatic plants.
Anything above 2 wpg without the addition of Co2 injection and you have to be very careful in controlling nutients to algae problems.
I think with 2.5 -3 wpg and Co2 you can pretty much grow anything.

With regard to the bulbs, in terms of plant growth, it's generally agreed any Daylight bulb with a color temp of about 6,500K is fine for plant growth. I would definately get rid of your warm white bulb. These generally have a color temp of 4,000k which is of not my=uch use to the plants, but apart from that will give both plants and fish an ugly washed out color. I would dump it purely on "artistic" grounds.

Having said that Keith makes a good point about reliability and longetivity. Most "normal" tubes will lose about 20% of their brightness very quickly and then slowly lose intensity until they no longer work. So it's reccomended that these bulbs are changed every six months to maintain a steady level of intensity. In this case specilized bulbs may offer as much or more value in the long term.
In my own case I always used Daylight tri-phosphor bulbs. These are more expensive (probably on a par with the LFS bulb price) but I liked the fact that they are about 20% brighter then a normal bulb, they don't fade in intensity as fast so have a longer life, and they produced a very pleasing color rendering which really showed off the colors of fish and plants. I've since changed to PC's mainly because it was the only way I could get sufficient light output in my odd shaped tank. They do a good job but I prefered the look of the tri-phosphor.

HTH

---

Some days you're the pigeon and some days you're the statue.

Remember that age and treachery will always triumph over youth and ability.

Hi,
Ben answered your question about watts/gallon with the
chart that he included.
Plants make use of the red and blue part of the light
spectrum. Red light is absorbed within the first few
feet of water. Blue light penetrates deeper.

Most of the "plant lights" that are sold in stores
are for terrestrial plants, and have a peak in the
red part of the spectrum. These are the lights that
give off a pinkish looking light.
Bulbs in the blue part are all 10,000K and higher.
These are generally used for Salt Water tanks especially
those that house corals, and/or other invertebrates.
They use this bright light to manufacture algae and
other nutrients that they live on and provide some of
their striking colors.

In a freshwater tank, with very high "K" rating bulbs,
some greens of plants can be washed out and appear
the same color as the "reply" button at the top and
bottom of this page. Generally speaking, to provide
truer color rendering, you would use lights that
fall around 6700-8800K. With light in this area,
you get a mix of all parts of the spectrum and to the
human eye, the greens are truely green and not washed
out.

As far as where to purchase your bulbs is concerned, it
depends upon how much money you have to spend. What Keith
said is also true. If you purchase cheap stuff, then
it may not last, or perform as well as the more expensive
stuff. Having said that, you can walk into any hardware
store and purchase flourscent tubes that are labeled
"DAYLIGHT" or "SUNLIGHT", spend less, and get the same
"K" rating as the some of the "aquarium " bulbs sold
at the LFS for much more. The daylight & sunlight bulbs
are rated at 6700K.
Flourscent bulbs shift spectrums as they age.
Most folks change their bulbs every 12 months.
If you use more than one bulb on your tank, you should
stagger their replacement. If you replace all the bulbs
at once, the plants, and fish can go into shock. It's
kinda like you stepping out into the bright noonday sun
from a dark cave, it takes a while for your eyes to
adjust to the bright light. Plants too need time to
adjust to the increased intensity, and the fish could
spend more time in shaded areas until they acclimate.
Also, having said that, other folks run their lights
till they completely fail and then replace them.
It's up to you and how much money you have available.

Frank


-->>> The Confidence of Amateurs, is the Envy of Professionals <<<--

Thanks for your replies!

So I'd conclude that two tubes for a 4' tank, with an attempt at a DIY c02 rigged up to the filter intake will suffice for decent plant growth

With CO2, is any better than none? I plan to start with the 2l pop bottle recipe. Not sure how this pans out across 45g but surely the plants will benefit?

Hi,
Yes "any is better than none." However, you need to inject
the CO2 in the output of the filter, not the input. If you
inject it into the input, it will soon lock up the filter
and the filters pump.
The idea with CO2 is to keep it in contact with the water
for as long as possible. That is done by either using a
reactor ( a container with many passages that has the
tank water pumped through it) or using what is called
a diffuser. A diffuser is similiar to an airstone in
operation, in that it breaks up the gas into very very
tiny bubbles that are subject to the currents within the
tank. However, the Diffuser is designed to withstand the
effects of the gass. A really good diffuser is made of
slintered glass and is much more expensive than an
ordinary airstone.

Frank


-->>> The Confidence of Amateurs, is the Envy of Professionals <<<--

Hmm, I understand what you say about the air in the filter system, but I read that on an article about DIY co2

Ok no worries though, shall just have to give it some more thought on getting the co2 circulated/into the water etc.

Many thanks Frank!

You can simply bubble the CO2 into the intake a of a small powerhead or make a DIY reactor chamber, it's very cheap, see "viewtainers"(search) they sell for sending maps, keeping nuts/bolts etc.
Cost about 2$ and a drill or hot nail to make the holes.

Plug the light and powerhead into the same timer.
That way you can have semi automated CO2.
Plants do not use CO2 at night.

I'd use 2x 2liter bottles of DIY. Make the brew for one, then stagger the next for the follwoing week, that way it's fairly even.

2.8 w is plenty of light.

If you are going to buy a plant bulb for the tank, get a triton.Has the best color to your eye and does well on growth. They run till they die. I mix then with a cool white for a nice color balance but they can be used alone also.I'll replace the cool white about each 6 months.
A 6500K daylight works just as well as those pricy bulbs also.

The color temp is not an issue for the plants in terms of growth or algae, that's all contrived to get you to buy something.

What it does do is allow your eyes to view good colors, so the light looks good to us, the plants will make do with any most light as long as it's red(~670nm) or higher energy(bluer, UV, etc) So a 6500K is typically what many folks like, some are now tending towards higher and higher color temps these days, it use to be 5000K was just rightThen 6500, then 8800, some 10,000. These K rating don't tell you a whole lot, but plant growth is the same. We did a simsilar study and another botany lab did one comparing all the special plant bulbs vs cool white.

They both found no differences in growth rates.
I've never found any light to cause algae any more than another bulb.

regards,
Tom Barr