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Re: Your suggestions for lighting please
>I guess the rule of thumb usually tossed around for lighting is 2-4 watts
>per gallon. If I split the difference and aimed for 3 watts/gallon that
>would mean 225 watts. My first question is is that a reasonable figure?
There is a good graph of watts/gallon for various tank sizes at
http://www.thekrib.com/Plants/Tech/Lighting/
Your figure sounds reasonable to me, but some of it will depend on the type
of plants you want to grow.
>Assuming 225 watts is my target I could get close to that with 4 55w compact
>fluorescents. I could also do 2 96w CFs plus a 28w CF. Alternatively, using
>VHO fluorescents, I could use 2 110 watt bulbs. With metal halides I'm not
>sure. Two 175s would probably be too much. A single 250 watt bulb is in the
>ballpark but I don't know if a single bulb will work well for a four foot
>long tank.
Most of the MH reflectors will only cover about 2x2 foot areas with even
coverage. Plan on using one MH bulb per 2' of tank length. I am getting a
125g set up now that will be lit with 3 175 watt MH lights, and I'm going
to use the spillover to grow some terrestrial plants with their roots
hanging into the tank. If you try to use a single 250w bulb you will have a
very bright spot under the bulb and very dark ends of the tank where the
light levels fall off.
The CF lighting is probably going to give you the most even lighting.
Personally I like the "wave sparkle" effect that MH provides. I plan to use
a few CF lights interspersed with the three MH lights so that I can step
the dawn/dusk (first CF, then bring on the MH with the CF for mid day, then
turn off the CF a bit later, and finally turn off the MH and dusk). MH
lights don't turn on instantly though -- it takes about 1-2 minutes for
them to come up to full intensity. There are some strobe-like flashes when
the ballast/ignitor strikes and arc in the tubes though.
I would stay away from VHO these days. The cost is too high in my opinion
due to the need for frequent bulb replacement. VHO is said to get about 6
months per bulb, I have found the CF to last about a year, and I have a 3yr
old 400w MH bulb (used for terrestrial plants) that is still going strong.
MH is probably cheapest in the long run.
>[cost/heat/dimmability/etc.]
>Anything else you'd include? Your comments on all of these factors as they
>relate to my various options would be greatly appreciated.
CF lighting is very affordable when done DIY with the AH Supply kits. I
have been very happy with the 55w lights I got from them. MH can also be
very cheap when done DIY. There is no reason to spend the huge $ at an LFS.
Just for example, I get my 175w MH ballasts from a local electrical supply
house for about $17/each, and it's a complete kit of ballast, ignitor, and
mounting hardware. The mogul sockets with the high-temp pigtails are $14,
and reflectors are about $25 from mail-order aquarium places. The only
tricky part is that you have to use 105º cable from the light to the
ballast. I like to use water proof cable here, and bought a spool of the
stuff for about $60 for 250'. I am using a surplus aluminum enclosure to
house all three ballasts.
As for dimmablility, I don't know of any CF or MH ballasts (besides the
strange coralife unit) that can dim. Icecap makes the Icecast to dim their
VHO ballasts, so you will have to go VHO if you want to dim the lights. I
have not heard anything conclusive saying that the start/stop of lighting
is bad for the plants or fish, so dimming is of dubious value.
>Concerning cost, I'm somewhat price sensitive but not overly so. If one
>solution differs from another by 10 or 15% I'm not going to sweat it. If one
>is twice the other, I'll give it some consideration.
You can save more around 70% over LFS pricing going DIY with any of three
types of lighting you mention. DIY MH and CF are approximately equivalent
in pricing to set up. I havn't used any VHO stuff in a *long* time though,
so I can't say what the cost to do a new VHO setup is these days.
>Regarding aesthetics, I have noticed in some LFS displays that the metal
>halide equipped tanks have a bit of shimmer that is appealing. That wouldn't
>be an overriding factor for me though.
You don't get this effect with either VHO or CF -- both are too even. I
have used some small halogen lamps in addition to CF to get the effect, but
I don't think it is worth the trouble. MH will always provide this effect
due to the point source nature of the bulbs.
I would stay away from any ballasts that lock you into one specific bulb.
Use the standard ANSI ballasts (M57 for 175w) that will light any MH bulb.
The cost to move to one of the new solid-state ballasts isn't really worth
it -- it would take many years to make up the cost difference with the
electric savings.
If you build a hood be sure to use fans. Quiet fans. CF bulbs will last
longer if they aren't baking all the time, and I wouldn't want enclosed MH
lighting running without some forced air circulation. My 125g is open-top
so I just suspend the fixtures about 12" above the tank and heat is not a
problem. Let me know if you need any sources for DIY parts.
-Bill