Can You Increase Lighting Hours To Compensate For Low Wattage?

[PaulQ]

My tank has a 20w fluorescent light (FloraGlo). I've read that the general rule is to have 2.5w of light for every gallon. That would indicate I should have at least 60 watts of light. Obviously, I am not even close.

Can I compensate by leaving the light on for 14 hours? 16 hours?

I know it varies by plant but can you give me a rough idea if this formula works (more time to compensate for low wattage)? I wish I could tell you what plants I have but I don't know their names - 5 different kinds. One is a Java.

Thanks!

 

[OldMan47]

The simple answer to your question is a big NO. Extending the photoperiod will affect plants but will not allow you to grow medium light plants under lower light levels.
Another factor you may want to explore is the light requirements of plants. I have tanks that get extremely high lighting, like up around 2.5 WPG and other tanks that barely run 1 WPG. Both tanks get good plant growth. The big difference between these tanks is the plants I put in each one. At 2.5 WPG, you are in the medium to high range of lighting and can grow almost anything that strikes your fancy. At 1 WPG, you are dealing with low light and must stay with low light plants. I have no idea where you got the idea that a planted tank should run 2.5 WPG of light as a general rule, I hope it wasn't here. Each tank has its own needs and its own lighting demand based on the plants that are present and the substrate and water column fertilizers that are available. Some plants also do better in harder or softer water. Matching your plants to the conditions you can provide is the key to having a lush growing planted tank.

 

[PaulQ]

I have no idea where you got the idea that a planted tank should run 2.5 WPG of light as a general rule, I hope it wasn't here.

It was in one of these forums, might not have been this one. I remember thinking how bright my tank would have to be to fit that bill! I've been reading so much, it's getting blurry.

Ok. I take your advice, OldMan, as the expert word!

I am going to post a photo of my tank shortly and just see what everyone has to say. I know I've made mistakes and I am curious to know if I'm at least on a path to success.

 

[OldMan47]

I am no plant expert Paul. I am merely a fish person with a bit of success following other people's advice on plants.
I became intrigued with Diana's methods and actually bought her book over the internet. It gave me plenty of insights into what was going on in my planted tanks and made me willing to try her method on one of my tanks. I now have 6 tanks using what amounts to her methods. The high tech approach to plants always struck me as too much work, but I do have a high tech tank that I experiment with. It also gives me decent results but is confirming my own concept that high tech planted tanks take way too much work.
I get about the same results in my NPTs and spend far less time caring for them. With a total of 25 tanks up and running, time spent to maintain each one becomes a critical parameter for me.

 

[waterdrop]

Yes, just in case you check this again Paul, I'll add another voice of agreement to OM47's comments. You are much more likely to be getting it right at about 1 watt per US gallon and short lighting periods. Some people start with only 4 hours and only add hours as long as they don't get algae, very slowly working their way up to maybe 6.. 8.. 10 hours or so.

~~waterdrop~~