[middlearth]

I have a Coralife fixture with 2 36" T5 HO bulbs. I've been using the bulbs it came with- 1 blue actinic and 1 daylight, both 39 watts.

I have Congo tetras, 1 apistogramma, 2 cories and an L134 pleco.

I'm not adding CO2. I'm using Flourish tabs and the Flourish micronutrient supplement. I stopped using Flourish excel because I heard vallisneria does not like it.

The plants I have seem to be hanging on, but certainly not lush growth.
My understanding is that if I'm not adding CO2 I don't want too much growth. . . .

Should I replace the actinic with another daylight/plant bulb to help out?

Also, do these T5 bulbs need to be replaced every 6 months, or are they good for longer?

Thanks much for any input!!

-Gwen

 

[nodima]

You should have plenty of light, depending on the quality of the reflectors in the unit.

You should indeed replace the actinic with another bulb more suitable for plant growth. However, you will want to keep an eye on your photo period to avoid algae issues. Take some time to look around at one of the planted aquarium websites for the more detailed and specific questions around nutrients and the needs of your plants etc.

Two good ones are

The Planted Tank http://www.plantedtank.net/

Aquatic Plant Central http://www.aquaticplantcentral.com/

The things you have "heard" concerning plants not liking excel are likely not true, particularly out of a specific context. The idea about growth rates and CO2 is more around how much trimming work you want/need to do, than it is about the health rates of plants - you always want your plants to be growing and healthy, not barely hanging on. The trick is to work with plants that are not so fast growing that trimming becomes a daily chore. CO2 is not a magic wand, but it does help provide plants with needed carbon in an effective way.

 

[hollyfish2000]

I agree with the previous poster that you need to replace that actinic with a plant spectrum bulb.

Also true that you generally need to replace bulbs every six months or so.

I've also heard vals don't like excel, but apparently my vals don't have access to the internet and do just fine.

I personally don't think 80 watts over a 46 bowfront is enough light for most plants beyond maybe anubias or java fern. Your plants might "hang on" but may not thrive. I've personally had trouble with low-light tanks without C02. They tend to grow a lot of BBA, which I detest!!

You might try replacing the one bulb, leaving the lights on for 8-9 hours, dose daily with excel and monitor algae growth. You can make adjustments from there based on what happens. Be careful about dosing the water column with ferts in a low light tank -- sometimes you're just feeding the algae. The root tabs (and the right substrate for plants) is more important IMHO.

Good luck!

 

[Number6]

Apologies in advance for using your post as a teaching tool, hollyfish. I just wanted to speak to several items that your post contained.

Also true that you generally need to replace bulbs every six months or so.

100000% false. The spectrum starts to shift after around 6 months or more, depending on the quality of the bulb, but that doesn't mean a thing if the lamp still puts out light that plants can use. I don't replace bulbs until the ends blacken or the bulb burns out and my freshwater plants love it. I frequently take bulbs that are older than one year off my reef tank and move them to my freshwater tanks. Lately I've been growing plants under LED, so pretty soon my habits will be a thing of the past. Where this "6 month" myth came from is from folks who eek along at or just below minimum light thresholds of certain plants and when the lamp's spectrum shifts out of the ideal, the plant gets overrun by algae.

I personally don't think 80 watts over a 46 bowfront is enough light for most plants beyond maybe anubias or java fern.

I definately disagree. I can produce a ton of light using 80W and if it's shining downwards, I can grow most "medium" light plants.
80W measures power consumption, not light production, so there are many instances where 80W of usage won't make useful light or direct it downwards and those will fail.

Be careful about dosing the water column with ferts in a low light tank -- sometimes you're just feeding the algae. The root tabs (and the right substrate for plants) is more important IMHO.

Good luck!

Fantastic advice! I second that... IME, I've cured more low light planted tank disasters simply by eliminating all additives than with any other tool.

The corallife units (IME) do not tend to have good ballasts, nor very good reflectors. They also ship with bulbs that do not suit my tastes often being heavy on the green! The corallife units I've owned have been canibalized for parts and built into wooden hoods. One only needed a better reflector... the other needed a better ballast. If you cannot canibalize it for parts, definately replace BOTH bulbs with a decent lamp.
I quite like bulbs like this:
Giesemann Powerchrome 36 Inch 39W Aquaflora T5HO Fluorescent Bulb

 

[nodima]

Agree with Number6 on all counts:

Watts is not a measure of light output, it is a measure energy consumed. The T5 bulbs are far more efficient than the old T12 to start with, so the WPG "rule" does not apply.

Check out this thread for more detail than you ever wanted to know about light and planted tanks:
http://www.plantedtank.net/forums/light ... 12-pc.html

A pair of T5s over a 46 bow will be bordering on High light.

And as for replacing bulbs, nope. Run em til they die.

 

[hollyfish2000]

WEll, thanks for the update on lighting. I use the Coralifes and replace the bulbs every six months . . .