Actinic bulb in freshwater planted?

[aquaholic]

Why does everyone say these have to be replaced? are they uselless in planted tanks or do they just look bad?? they do have the same wattage as the regular bulb so I was wondering why do they need to be changed out to regular daylights?

[Zenz]

It looked really ugly in my tank. It's really bright and washes everything out. It's just too bright/white/blue? for most fw tanks, imo.

[justahannah]

Plants need light between 6,500-10,000K wavelength (most bulbs labeled "daylight" are in this range), that's what they process for photosynthesis. Actinic is like 460-490K, way too blue for the plants to use, so your plants won't grow. They also give a very blue hue to everything in your tank. Some people like a bluer look and will use both daylight and actinic, if their fixture holds multiple bulbs. Others think the daylight look is best...but that's asthetics. When it comes to what your plants can efficiently use for growth, you want to stick with the 6,500-10,000K spectrum.

[Phyroath]

I have Actinic light on for viewing in the evening time after the normal daylight is off. Mine is a Toshiba Aquarium T8 Bulb claimed to enhancing the look of aquarium plants - are there any other problems having Actinic light on such as algae promotion etc. I would like to learn from this thread too.

[phanmc]

Plants need light between 6,500-10,000K wavelength (most bulbs labeled "daylight" are in this range), that's what they process for photosynthesis. Actinic is like 460-490K, way too blue for the plants to use, so your plants won't grow.

Plants use light within the 400-700nm spectral range, so they can utilize the light from actinic bulbs. The problem with actinic bulbs is that they provide only light within the 460-490 range and plants need more than that, so using actinics exclusively is probably bad.

I'll get around to testing actinic bulbs with a PAR meter in the near future to see their real impact.

6,500-10,000k is the K rating, an approximation of the color of the light and has nothing to do with what plants need.

[aquaholic]

so you mean using only actinic bulbs is bad but using both regular and actinic should be ok?

[nguyendetecting]

yeah, provided that you provide enough light.

[James0816]

Actinics are mainly used on saltwater setups. You can use them on freshwater but they offer no real "benefit". Use regular daylight bulbs instead.

However, if your tank has night time occupants, an actinic bulb will good to use. I use one on my larger tank strictly for night viewing.

Use during the day is really a waste IMO.

[justahannah]

Seems like I just read the PAR vs. K rating discussion not too long ago with the impression that while PAR rating is the accurate way to go, your average fishkeeper is not going to own a PAR meter (as well as most bulb packaging does not contain this info) and that the Kelvin rating is a close enough approximation that plants do very well within that color range. Given the pride that goes with a beautiful, well planted tank, if another type/color range of bulb was more effective, I'm sure people would switch if the info was out there, but for the moment, the K rating is the industry standard. I would definitely be interested in seeing the results of the PAR test on actinic lighting, always good to increase the knowledge base. I'm also speaking from personal experience, I had a 10k/460 CF light in my fixture for close to a month (it's what came with the fixture, couldn't afford the new bulb) and I saw very minimal growth. After switching to a 6.7/10k bulb, my plants took off like nobody's business.

[aquaholic]

the question is will it do any harm? If wpg are reached with the regular daylight bulbs, and having more light will only increase chance of alea. will it hurt to keep the actinic bulb on with the other bulbs during the day if you like the color?

[justahannah]

That I don't know. I know people with marine tanks and actinic lighting also battle algae issues so it may increase your algae growth...but I don't know if saltwater algae utilizes light differently from freshwater algae. I didn't notice algae issues while I had the partial actinic lighting...but my lighting has stayed at 2.1 WPG regardless of spectrum. If you increase your WPG, even if the increase is w/actinic lighting, I would think algae would find a way to utilize this unless your plants are outcompeting the algae for the other tank nutrients. I'm hoping someone with more experience with actinic will chime in here for you.

[WaterBug]

I have 2 65 watt daylight bulbs and 2 65 watt actinic bulbs over my 75g planted. The actinics do not seem to contribute to my wattage totals but neither have i seen any major algae outbreaks. It does not seem to do any harm as far as I have seen (they have been in for about a year..and will continue to be there till I can afford new bulbs.)

[phanmc]

Played around with an Apogee PAR meter and the results are surprising. I tested Current's 27w dual daylight and actinic bulbs in a 12g Aquapod and the results in PAR were pretty close, within 10%. Maybe the reason why people think using actinics causes algae is because they have too much light and didn't factor in how much the actinic bulb is actually contributing.

Since one of my lights have gone out and I don't have a replacement yet, I'll see what kind of impact using an actinic in place of one of the dual daylights will have. Mixing the two does look kind of nice.

[Spewn]

Maybe the reason why people think using actinics causes algae is because they have too much light and didn't factor in how much the actinic bulb is actually contributing.

I'd bet that's it, considering most of the time this comes up the suggestion is to treat the actinic bulbs as only 50% of their wattage.