Ballast and CF Bulb Wattage

[tackful]

Hi,
I am trying to slow down the growth in my 29 gal tall tank under a 55 watt Brite Kit. A few months ago I changed down to a 45 watt bulb with the same ballast, but haven't noticed any changes at all. Would the ballast still be driving the 45 w bulb up to 55w? I don't have experience in this type of electrical theory. Thanks.

 

[TwoTankAmin]

The wattage refers to the amount of electricity used to drive the bullb. The amount of light is measure in lumens. Try and find spec sheets online for both bulbs and compare their lumens.
https://www.energy.gov/energysaver/lumens-and-lighting-facts-lab

 

[dougall]

The changing of the bulb is unlikely to affect the amount of light without changing the ballast, you are just going to lessen the lifespan of the bulbs.

You can use less efficient reflectors around the bulbs, raise the light fixture, shorten the photoperiod, or stop using PC bulbs and get dimmable LEDs.

 

[TwoTankAmin]

One more trick which I use on my old power compacts to "dim" them since they are not dimmable I put a sheet of white paper ounder the light on the glass. This reduces the amount of light and should not change the spectrum as far as I can tell.

I have been doing this on some older T08 fixtures as well for a number of years, U have never had the paper come even close too igniting or even darkening. I tend to use legal size sheets.

One last observation about planted tanks. Nobody every talks about the fact that plants grow up and sooner or later things like anubias will reach the surface. The problem is once they get over a certain height theey become covered in algae as the intensity of the light increases to the plant the nearer it gets to the source. I have anubias that have broken the surface on 75 and 150 gal tanks. I do not do sword pants any more because they always hit the surface and take up too much room. When the anububias hit the surface in my original 45 gal. tank I gave two away to friends with big tanks.

 

[FreshyFresh]

How long have you been keeping the light on?

From the sounds of the wattage, that's not a crazy amount of light over a 29g, but PC's do put out some lumens, which like said, is what matters.

I have a 55gal full of anubia that grows like crazy under a 48" twin tube T8 fluorescent, with only one bulb attached. 2 bulbs was resulting in algae as T TwoTankAmin described. I run them for 8hrs/day.

 

[tackful]

Thanks everyone for all of these good ideas. What I have done is build a light support over the tank using narrow, inexpensive aluminum channel from the local hardware store. Raising the light 3" hasn't slowed down growth, possibly because it is no longer passing through the former plexiglass cover. Wiii raise it up an additional 2' and see what happens.
If this doesn't prove satisfactory, I will have all of this input to fall back on. Thanks again.

 

[TwoTankAmin]

You know that old movie/story line re crossing over after deat? Well plants when they are alive go towards the light. O rmaybe it's grow towards the light....... Sooner or later they will reach the surface if they can and some will even go beyond that barrier.

 

[fishorama]

As somebody said, maybe a shorter photoperiod would help. I do 6 hours or so at most. & I'm a lame-ish fertilizer & that helps too.

 

[tackful]

Currently at 7 hrs. That is something I could try. Recently installed a glass plate directly underneath the bulb to see if that would somehow slow things down. Too soon to tell. If inot, I could try smudging the glass with some very fine sandpaper.

 

[fishorama]

Instead of sanding/etching the glass permanently, you might try tape strips or mesh of some kind to block some of the light (beware the heat!). Raising the light may help...but will widen the spread, not sure that will be much use unless it quite a bit higher (like 5 or 6 inches)