# 13w 23w 7inches 10inches or?

1067 Views 10 Replies 4 Participants Last post by  tjurhs
Hi guys,

I worked all day yesterday getting my plant tank cleaned and rebuilt, I've been making "newbie mistakes", cause that's what newbies do.

I have a 10gal tank with Anubias, Anacharis, Watern Fern, and Dwarf Baby Tears.

I did some reading here in the lighting section and found that I should use bulbs in the 5000K to 6500K lumens region, so I got one of each.

At my local Lowes they had both 13watt and 23watt 5000K and 6500K bulbs. I bought the 23 watt versions. So I currently have a 23watt 5000K CFL and a 23watt 6500K CFL hanging over the tank in those industtrial looking aluminum domes with a clamp.

Anyways, that gives me 4.6watts/gallon, maybe high, idk?

If the watts/gallon is too high, I can raise the lights from 7inches to as much as 10inches (more if I really had too).

but I haven't really found any literature posted on the internet that tells me how high to hang them???

I could use the rull of thumb that electromagnetic energy (light) falls off as a function of 1/(r^2), but I don't know what value I want to get to...

anyone able to throw a little help my way?

Thanks much! Todd
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The 13W one is the correct one and only one of them IF the fixture you speak of
is the one which has the bulb virtical. For some reason( and I just found this out a few days ago) the ones which hold the bulb horizontal cut the light output more than half.
BTW the WPG thing was designed to go/w the T12 and T8 bulbs so it's off somewhat
with other bulbs and also actually was designed for tanks the shape of yours and so
that rule doesn't work well with tall type tanks either. Was never a true mathematical formula that applied across the board. Something like the one inch per gallon rule for
fish. Obviously a 10" Oscar doesn't belong in a 10g tank.
This is what is used now and it does list your light bulb.
http://www.plantedtank.net/forums/showthread.php?t=184368 But does not include that horizontal thing.
But using that rule, I grow algae intentionally and have 3.6WPG
So if you want algae you will get it with two of the 23W ones on there.
If you don't, then use one @ 13W about 10" up from the tank and if no algae shows up but the Baby tears doesn't grow, then lower it some. Like to half of that.
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back to Lowes
dual 23w's on a 10?

A single 10 or 13w should suffice. I'm running a single 10w maybe 6" above the water line and I'm getting hints of surface algae on the glass. I'm switching over to a 13w but that's only because I'm replacing the 10 with a 20 high.
btw, Walmart has the GE 6500k 3pk for \$7
Is there a chart or equation somewhere or rule of thumb that says how high above the water surface a single 13watt CFL should be placed
Trial and error.

Set it up to where your plants look good and gets good light coverage and if you don't get any algae, leave it alone. If you do, raise it up an inch or two.

One of my Nano's was getting algae at the gravel line so I raised my light from 6" to 8" and its all gone now.
and that sounds like a rule of thumb to me

thanks!
now I have one 13watt 6500K CFL bulb
Post some pics when you get it set up! :red_mouth

I was in Lowes yesterday they have both 5000K and 6500K in 13W and 23W @ \$7 and \$9 for 3 pak. Also have some 8" clamp-on domes as well as the usual 12" or whatever. Im about to set up a 20H and may go the cfl route.

four different plants, and three Nerite snail, not real fancy, but a start

Sent from my iPhone using Tapatalk
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