watt/gal. and "on time"

[SimonWoodstock]

My light went out yesterday, so I have to get a new one. The 15 & 20gal post helped me with some of my questions. I do have 2 more.

I just have (had) this 18" 15w flora-grow bulb on my 20 gal.

I take it my 15w bulb that gave out was giving my tank 1.5w/gal...i think. I can't get a new hood or whatever at the moment so I will have to stick w/ the same thing.

Would running a light that weak a little longer help any? I currently run it 10-10.5 hours a day, that is the longest I tested without having problems like algae.

And would one of those "grow" lights give off the right spectrum for my plants?

A list of plants I know I have:
1 small Water Sprite Ceratopteris thalictroides
Several Aponogeton Bulbs ?
Several Dwarf Lily-Hybrid Ulvaceus ?
2 plants i dont know what are. they are thick, broad leaf plants. stems and leaves are thick enough not to move in current.

thanks

[odessa]

If you have a 15 watt bulb over a 20 gal you ahve .75 of a watt per gal.

IME running a light oif any intensity over 10-12 hours makes no difference in growth and may actually hurt the growth of many plants, as they need a night/day cycle like every other living thing.


If the Grow lights you mention are in the 5000k -6500k rating they will be fine.

[TKOS]

I would skip the growlight bulbs as they generally cost a lot more and see if you can just find a daylight bulb at the Home Depot or some place similar where it will cost a lot less. Of course the grow bulb will still be a fine choice if you don't mind spending the extra money.

And I agree with Odessa that leaving the light on longer won't achieve anything extra. You will just have to be happy atthe moment with lower light plants until you can make an increase in the light you have.

[SimonWoodstock]

For some reason I was thinking a 15w fluorescent bulb was actually putting out 30w or something like that. I don't know, I just picked up one of those lights for aquatic plants at wal-mart. For now, I will just have to deal with it.

thanks