Adiquate 30" Lighting ?

[HooKooDooKu]

I'm looking to setup a 20L gallon planted tank.

I'm only interested in plants that need medium level lighting (such as Corkscrew Vallisneria) or lower. I'm also interested in keeping the light level low enough that I do NOT have to even think about investing in CO2 equipment. Does this mean I need to target having about 2 watts per gallon (based on NO florecent lights) or do I need more?

From what searching I've been doing, it seems like perhaps one of the most cost effective (short term) light sources is T-5. But what I'm not sure of is if T-5 means HO. I have read that when using HO, you want to multiply your wattage by a factor of about 1.75 to equate to NO.

One specific light fixture I've come across I would like your input on is this Aqualight with Colormax & 6700K Fluorescent T-5 Lamps - 18W - 30 in. | T5 Lighting | Lighting Systems | Aquarium - ThatPetPlace.com dual 18 watt T-5. I'm thinking that I just have to get a regular All-Glass Versa-top (12x30) and place this light on top of it. If the T-5 is NO, then I've got just enough light to me close enough to medium. If the T-5 is HO, then I've got about 3wpg equivilent output, which I think is low enough to at least not require CO2.

What's your feedback?

 

[Purrbox]

There is both T5 and T5HO and the fixture should state which it is. The factor that you are multiplying by, is probably overly high. I should think that if you aim for the 30-40 watt range (unadjusted) you should be fine without CO2. Worst case you could invest in some Flourish Excel, and use that for your carbon supplementation instead of injecting CO2. A 20 gallon is small enough that it wouldn't be overly expensive.

 

[HooKooDooKu]

I've since figured out that there is T5 and T5HO.

I've figured out that this is regular T5 and not HO based on cost. Replacement tubes of this size are in the ballpark of $20 each for HO, while regulars are in the ballpark of $10.

So with this fixture, I'll have a total of about 36 watts over a 20 gallon tank. That's a few watts less than what is possible with the All-Glass twin tube strip light https://www.drsfostersmith.com/product/prod_display.cfm?pcatid=13612&prodid=6842&catid=3 which accepts upto 20 watt bulbs, but 2 watts more than the 17watt pair that come with that light strip.

For now, getting the T5 is making for a smaller initial investment. The light fixture is a few bucks cheaper, but based on it's size, I can use a standard Versa-top I found locally for about $10 rather than spending more to get the more expensive twin-tube versa-top https://www.drsfostersmith.com/product/prod_display.cfm?pcatid=13818&prodid=6918&catid=3.

Besides, the T5 appears to be full 30" length tubes, while the other uses 24" tubes. That should mean the available light is spread out better with the T5 rather than the All-Glass twin tube strips.

But on the down side, it looks like replacement lamps for the T5 are a little more expensive, and definitely harder to come-by.

So for now, I've ordered the light fixture from www.thatpetsplace.com. There prices generally seem to be pretty good, and they have a special providing free shipping if you spend $100. I hit that easily by adding some replacement bulbs now and throwing in a new heater.