# T5 vs PC lighting for 20G



## Harry Muscle (Mar 21, 2007)

I'm doing some homework in preparation for maybe getting a 20G open top tank (the actual tank dimensions would be aprox. 24x14x16). So far the choices for lighting seem to be:

28W PC (Aqualight 20" fixture) - aprox. 2100 lumen
24W T5HO (Aqualight 24" or Hagen T5HO Glo 24" fixture) - aprox. 2100 lumen
36W PC (Aqualight 24" fixture) - aprox 2700 lumen
48W T5HO (Aqualight 24" or Nova Exteme 24" fixture) - aprox. 4200 lumen

I'm hoping to get as much light as I can without needing to use Excel (since it kills my vals and I think also mini pellia) nor do I want to use CO2. So basically I'm looking for medium light ... ish.

The plan would be to have the water about 2" below the top of the tank (to prevent jumpers) and have the light elevated on legs (I'm not 100% how much height that will add, but I'm guessing 2" to 3").

I've done some lumen per square inch calculations since they are way more accurate than the old and outdated watts per gallon idea. My old 55G tank which had two 4 foot 32W T8 bulbs over it had about 10 lumen per square inch (LSI). It grew most but not all plants and I would have considered it to be low light bordering on medium.

That means that the 48W T5HO fixture would give me about 12.5 LSI, which is about 25% more light ... I just don't know if that is too much light and would require CO2 and/or Excel (btw, I dose fertilizer regularly, so that's not a problem). Hence I'm looking for opinions. Also lumen per square inch doesn't trully tell the whole story and something is telling me that a 48W T5HO fixture over a 20G would be way more light than my calculations are telling me.

So if you were setting up a 20G open top tank and wanted as much light as possible without needing Excel or CO2, which light would you choose from the above list ... or is there maybe another light that you can recommend that's not mentioned.

Thanks,
Harry

P.S. There's also the Aqualight 24" T5 Normal Output fixture, which has two 14W T5 bulbs that should be added to the list.


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## igor.kanshyn (Jan 14, 2010)

In my experience, it's better to have as much light you can get. You can always cut a lighting period. 
Look at 24" T5 HO Aquarium Light Freshwater Plant 48W 2x 6700K as well.

BTW, how do you calculate lumens for those light fixtures?


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