[szenic]

Hello, currently have a 20L tank with a 17 watt bulb. Would it be too much light if I change the bulb to a 24watt? Tank measures 12x12x30. Light is pretty much right above water line (maybe one inch).

Do low light plants just prefer low light, or does higher wattage actually negatively affect them. I was planning on getting a range of low-high light plants.

Any advice appreciated!

 

[2in10]

You could go to 24 watts but it will require a new fixture since the ballast in your current fixture will not run the new bulb as intended.

You can lift the fixture up to lower the light level in the tank if the plants are having trouble. Generally they can handle a little higher light level without too much trouble.

 

[szenic]

Do you think the current 17watts would be enough for high light plants? Or only low-medium. Or only low? ?

And could you elaborate on what you meant when you said that the current balast wouldn't run the new bulb as intended? Sorry; newbie. The hood I have is the perfecto 30" hood if that helps. And the bulb it came with is the marineland f18t8 natural daylight bulb.

 

[Hoppy]

Fluorescent light hoods are made for one size bulb only. For any length of bulb there is only on wattage bulb available, in your case, it's apparently 18 watts. You can modify the light to overdrive the bulb, gaining about 50% more light, but that's all you can do, without adding a second bulb, which means a new hood or a second hood.

Low light plants will grow with less light than other plants, but they grow faster with more light. It would take a lot more light than we ever see to damage them in any way. When any plant grows faster it needs more fertilizers, and more CO2. The lack of one or both of those can lead to unhealthy plants and algae problems with high light.

 

[szenic]

Thanks for the explanation. I did see a 24"/20 watt t8 aqua-glo bulb on amazon. Would that not fit the hood I have? And if it does would another 2 watts make any difference?

 

[Hoppy]

Watts is just a measurement of the electricity used by the bulb, not the light it puts out. Unless you have PAR measurements for the bulbs you are considering you can't tell if it will be brighter, dimmer, or the same as what you have now. For example 32 watt T8 bulbs put out as much light as 40 watt T12 bulbs, and with any kind of reflector you get more light from the T8 bulb. But, both bulbs will fit in the same fixture.

 

[szenic]

Ah I see. Thanks for explaining. What kind of reflector could I get for my hood?

 

[Hoppy]

I don't know of any reflector you can buy for a T8 light, but you can make one out of cheap thin aluminum sheet, aluminum flashing, for example. You can then put two bends in it to make a \_/ shaped reflector and attach it under the bulb. I found that doubles the light from screw-in CFL bulbs. You just adjust the bend angles so that when you look at the bulb, you see the bulb plus a reflected image of the bulb at each side of it. Polishing the aluminum probably helps, but I didn't bother doing that.

 

[szenic]

I'll try that! thanks a bunch!

 

[szenic]

Can I use regular aluminum foil?

 

[Hoppy]

Can I use regular aluminum foil?

You can try anything you want to. I don't think aluminum foil is strong enough to hold its shape, so thicker aluminum, like flashing, will work easier and better.

 

[Steve001]

Ah I see. Thanks for explaining. What kind of reflector could I get for my hood?

Can I use regular aluminum foil?

Check any stores that sell party items. Look for silvered mylar balloons.
Or you can use this mylar sheeting
http://www.bghydro.com/BGH/itemdesc.asp?ic=HLMYC025-1&eq=&Tp=

 

[Hoppy]

Check any stores that sell party items. Look for silvered mylar balloons.
Or you can use this mylar sheeting
http://www.bghydro.com/BGH/itemdesc.asp?ic=HLMYC025-1&eq=&Tp=

Then you still need something to hold the mylar in the shape you want, like a bent aluminum sheet reflector, which is a better reflector than mylar if it is polished at all.

 

[Steve001]

Then you still need something to hold the mylar in the shape you want, like a bent aluminum sheet reflector, which is a better reflector than mylar if it is polished at all.

That's why I listed two choices. Obviously these two products won't work as a stand alone, they need support. I'm assuming they will acquire a reflector.
The mylar film reflects 98% of the incident light. Polished Aluminum the same. Mylar film probably uses aluminum.