Is having the lights on at ½ power for twice as long as full power equivalent?

[HHaley]

I have a question regarding the use of a Coralife Freshwater Aqualight Deluxe light strip in a planted 90 gallon aquarium.

My question centers around being able to run this light for a longer period of time at reduced power and still get the benefits of running it at full power for a shorter period of time.

At full power, this light strip has four 65 watt (6500K) bulbs. The total power output at full power is 260 watts. In a 90 gallon aquarium this equates to 2.89 watts per gallon (I’m ignoring the volume that the substrate consumes.)

I’m not sure of the units with this calculations but if you keep the light on for 7 hours at full power you subject the aquarium to 2.89 watts per gallon x 7 hours = 20.2. (Not sure of units).

I have found that at 7 hours, there will be minimal algae growth. The downside to 7 hours is that the aquarium is dark for most of the day since we elect to have the 7 hour period during the evening hours.

This light fixture has the ability to turn ½ the lights off. This would result in 1.44 watts per gallon.

In this reduced power state, I can run the lights for twice as long (14 hours) and subject the aquarium to the same total light energy. 1.44 watts per gallon x 14 hours = 20.2

My goal would be to run the lights for a longer time period while at the same time controlling algae growth.

Can anyone provide some insight (I was going to say shed some light!) regarding the impact this would have on growing plants by running the lights at ½ power for twice as long?

Is having the lights on at ½ power for twice as long as full power equivalent?

Thanks

[bettebulldog]

not at all.

[Scribbles]

Nope. But do you need that many wpg? What plants do you have?

Chris

[Wahter]

Is having the lights on at ½ power for twice as long as full power equivalent?

Thanks

Nope, not at all. Duration is not a substitution for intensity.



Walter

[HHaley]

At the current time, I have about 20 plants in the tank; mostly Amazon swords and other plants that my local shop recommended for a planted Discus aquarium. The tank has been set up for about three maybe four weeks. We started out with 10 to 12 plants and have added a few after each visit to our fish store. We were mesmerized by the beautiful planted tanks that we were seeing and wanted to try a high tech tank ourselves. We purchased the Coralife high output light strip, substrate material and even the heating coils for heating the substrate.

When we initially set-up the aquarium, we followed the recommendations and used the light for 11 hours a day on a timer. The first two weeks were fine. We went away on a small vacation and came back 3 days later to the beginning of an algae bloom. We immediately cut the usage of the light (at full power) to 7 hours and within a week 95% of our algae problem disappeared. The only alga remaining is the hairy or stringy algae that are growing on a few of the swords leaves.

While I feel that 7 hours a day is probably around the right amount of light to minimize algae growth, I’m unhappy that the tank is dark for most of the day when I would like to view the fish.

This is when I remembered that I have the ability to run the light at ½ power and I thought I could extend my viewing time with the lights on and keep my algae under control.

At the present time, my fish population is six 4” inch fire red discus, five corey cats and one bushy nose.

For filtration I have both an Eheim 2078 and an Aquaclear 500. The Eheim was just installed last week and by this weekend, we’ll remove the Aquaclear. We’re running both filters for a week to allow the biological filter media to become established before disconnecting the hang on back. We switched filters because we were told the surface agitation from the Aquaclear was releasing the CO2.

My next step is to implement a fully automated CO2 system once I determine what system to purchase.

[zn394]

In answer to your question no, it is not the same. However, the lower intensity lights will help the algae problem.

I have a similar situation with my 150 and 130 gallon planted tanks. At 384 watts of 6500K and CO2 in the 150, I had major algae problems. With the incorrect balance of lighting, CO2, and nutrients, algae is a distinct probability. I cut the 150's lighting to 192 watts of 6500K, eliminated the CO2, and the algae became manageable with the cleanup crew in the tank.

In the 130, which has only been running for a few weeks now, I set it up with 192w @ 6500K, no CO2, no additional nutrients, and a substrate of layered soil/eco-complete/sand with heavy planting from the start. There was a small growth of brown algae (diatoms most likely) and the green slimey algae 3 or 4 weeks in. I read somewhere that this was due to excess phosphates, so I added a phosphate removing filter pad a couple of weeks ago and the algae has subsided dramatically. There is also a cleanup crew in this tank of abn's and amano shrimp that were added early on.