dgphelps

Hi, I've read many threads and to be bluntly honest can't seem to get it. None of the situations relate well to mine so I am going to post what I've done and see if any of you folks who get it can help me out.

I have a basic 10 gallon tank setup for my yellow shrimp with an assortment of plants from my main tank. The tank had a very basic hood with a flourescent 15w tube. The light was very concentrated in the center and the plants grew super slow.

Today I stopped at my LFS on a completely untank related trip and saw they had 10 gallon incandescent hoods with the 2 x 15 screw in bulbs on sale. The hood design is better, the lights more centered and lifted higher with very basic reflectors, plus from what I've read, screw in is better and lends itself to CF bulb upgrades. Afterwards a stop at Target had me holding two GE "Daylight" 6500k 15 watt (60 watt equivalent) CF bulbs. When I got it all home, the CF bulbs fit great so I swapped it out and powered them on. It looks great, very even light spread, much brighter and slightly greenish in hue though my Flourite substrate looks nice and red colored.

Now when I try to figure out watts per gallon I am stumped. Does that mean I have two 15 watt bulbs so roughly 3 watts per gallon? Or since they are compact fluorescent at "60 watt equivalent" that I have 6 WPG and have effectively overdone this? I dose excel every other day. I'd really like to not do CO2 in this tank. Should I step back, return the CF bulbs and just put in the 2 15w tube incandescents that came with the hood setup?

I'd like fast growth in this tank to keep it full for the shrimplets, algae would be ok too, it's not a show tank.

Any thoughts? Thanks.

grim

they are fifteen watt bulbs so you have 30 watts over all

dgphelps

Even though it says 15W = 60W? It says the compact flourescent bulbs uses 15 watts but puts out 60 watts. Light output is 900 lumens.

hoppycalif

Those bulbs are sold as replacements for incandescent bulbs, but are much more efficient, so for the same light, less wattage is needed. The 15 watt CFL bulb is supposed to give about as much light as a 60 watt incandescent bulb. But our "watts per gallon" criteria is based on fluorescent bulbs, or compact fluorescent bulbs, so the watts for that criteria is the actual wattage of the bulb, or 15 watts.

The problem is that the screw in spiral tube CFL bulbs are not very efficient compared to a straight fluorescent tube. Much of the light they give is blocked by the adjacent spiral of the tube. So a 15 watt screw in CFL isn't nearly as effective as a straight fluorescent tube. I am using 2 20 watt screw in CFL bulbs on my 10 gallon tank, and I get no more than low light intensity from them. That is 4 watts per gallon, but is only as effective as maybe 1.5 watts per gallon of straight tube bulbs.

grim

you know hoppy i built a hood bassed on your ten gallon design for my 29 gallon tank using four 25 watt cfl bulbs and a make shift high gloss white reflector made from flashing and i can see straight through my gravel and have actualy been able to grow all sorts of plants so i am very happy with the cfl bulbs

hoppycalif

Yes, I realize that others have had good results with those bulbs. That is what is frustrating. It may only take small changes in the hood to make a big difference - more room between bulb and reflector, larger hood size, etc. And, I have even seen big differences in brightness of the bulbs between two of the same wattage, same manufacturer, same part number. My 10 gallon tank is jinxed.

dgphelps

I took the CF bulbs out and put in the 15w incandescent bulbs that actually came with the hood. It looked like a dankly lit cave. The difference in the visible light was crazy. I'm going to leave the CF bulbs in for now and see if I get any noticeable plant growth difference. Maybe later I'll put in two 25 watt CF bulbs. At least to my eyes the 15w CF bulbs are 4 to 5 times brighter than the previous hood with a 15 w tube and no real reflector and the incandescent bulbs.

Thanks for the explanation though Hoppy. I'm gonna cross my fingers in hopes my 10 gallon isn't jinxed.

-D

Agentkhiem

I have used the 6500K GE bulbs and let me tell you, they aren't that great for lighting...

I swapped the standard bulb in my Eclipse 5 with a 15 watt 6500K and all it grew were aglae and insufficient plant growth. Makes sense because all that white light is just parts of the spectrum that plants can't utilize well.. especially green. Aesthetically pleasing results, but better off using it as a supplement.

dgphelps

Any suggestions as to what brand / light spectrum I should go with instead? I was thinking of putting 2 20 watts in there in their place anyhow.

Agentkhiem

Eclipse sells Daylight bulbs that are compact fluorescent. This has a warmer tone which could help plant growth. http://www.thatpetplace.com/pet/prod/213954/product.web

This might also work too.. this is probably your better option:
http://www.thatpetplace.com/pet/prod/209773/product.web
Notice the reds and blues at 460nm and 640nm ranges.


Edit: There's a 20 watt version of the Colormax also..
http://www.amazon.com/dp/B0002DIHCS?...0&linkCode=asn