How Many Watts Do I Need

[Sasha]

I have a 46 gallon tank and really wanted to have live plants in it. My fluorescent light is only 25 watts and my tank is 18 inches deep. If I have to buy a more stronger light tube, I can do that but I don't know exactly how many watts would I need to grow plants that require high lighting. What would you recommend doing with my tank if I want to keep live plants? Should I get another light or keep the one I have?

 

[Lateral Line]

Typically, 2 Watts per gallon is regarded as "Medium" light. For "High" you'd want 3.5 - 4 Watts per gallon BUT that assume a regular light to gravel depth - your tank is deep, so you may need more. It depends what you want to grow, low plants that demand high light will need extra, tall plants that reach close to the surface you may get away with.

 

[Bol]

Sounds to me like you've got the 46G All-Glass bowfront, with the included bulb. If so, I've got the same tank.

I don't know exactly how many watts would I need to grow plants that require high lighting.

I agree with LL, you'd need 3.5-4.0 watts per gallon for high-light plants. That pretty much rules out NO (normal output) fluorescents.

However, at that light level, you will also almost certainly need to inject CO2 to keep the plants healthy. If you go the DIY CO2 route, you'd probably need three 2-liter-bottle generators.

What would you recommend doing with my tank if I want to keep live plants?

You should be able to successfully grow plants with your current setup, if you stick to only low-light plants. I've had very good results with hygrophilia polysperma, marimo balls, java ferns, java moss, crypt wendtii, anubias, wisteria, and hornwort. And "pretty good" results with amazon swords, water sprite, and corkscrew vals. Cabomba, not so good. It grew well enough, but got very "leggy".

If you want to go for higher light, the first thing you'd have to do is make sure you have the hood that's made entirely of glass (All-Glass calls it the Versa-Top), not the one that's mostly molded plastic. The plastic one isn't very plant-friendly, as not only can you not add a second light strip, but the molding around the single, narrow, glass "port" blocks significant light, even from a single strip -- when I switched to a Versa-Top, even with just using the standard light, the increase in the amount of light in the tank was pretty significant.

After that, what lights you choose are up to you. Me, personally, I wanted more light, but didn't want to be forced to inject CO2, so I just went up to a twin-tube NO strip, for 60W of light. I sometimes run that in conjunction with the original single strip, giving close to 2wpg, but the single strip hangs over the curved corners of the tank a little bit (and, not surprisingly, with 90W and no CO2, I started getting significant algae growth).

 

[Sasha]

Isn't 4 watts per gallon too high? I bought a couple Moneyworts, so I guess they would be fine with the light I have now. It's so hard to find plants that require low lighting over here. Is there anything else I need to keep plants alive and heathly. . . fertilizer, root tabs, CO2 injecter?

I do have the 46 gallon All- Glass aqaurium!

 

[Bol]

Isn't 4 watts per gallon too high?

Not for high-light plants. General consensus is you need about 3.5wpg at the least. Depends on the individual plants, of course.

It's so hard to find plants that require low lighting over here.

I hear ya. I went to an online source (but I found hornwort at PetSmart).

Is there anything else I need to keep plants alive and heathly. . . fertilizer, root tabs, CO2 injecter?

Depends on your plants and your situation. It seems the key to growing plants is achieving a balance of lighting, CO2, and nutrients.

For instance, if you have low light, then dosing nutrients with fertilizer probably won't help much, as the plants are living so slowly that they won't absorb them all (or, rather, they'll get enough nutrients from the water).

Similarly, as you increase light through the medium to the high range, and don't add CO2, then the light won't help much, as your plants will be essentially "starved", and have little need for the extra energy.

If you're sticking with the original lighting you got with the tank, then I personally would say that adding CO2 is not worth it (although it may help a bit), and the only fertilizers I'd even consider are:

Seachem's Flourish -- trace elements, sort of like a multi-vitamin. Dosed once a week, should be refrigerated.

Seachem's Flourish Excel -- A source of carbon, which plants use much the same way they do CO2. Dosed every day, or every other day.

Root tabs -- if you have heavily-rooted plants (such as swords, or crypts), the tabs can provide a long-term source of trace elements right at the roots. If you use root tabs for your root plants, you may find that the Flourish is of little benefit.

 

[Lateral Line]

I agree with Bol, CO2 is only going to be a marginal benefit, and apart from root tabs, your fish will basically provide pretty much everything else. Maybe a little Iron supplement from time to time.

 

[apisto_uk2]

Hi,

I think I have a setup that works reasonably well with noe need to add additional CO2. Also if you add extra CO2 you may need to reduce fish stocking levels.

My planted tank recipe.

1. Quartz gravel - for good root growth
2. Silver sand and Duponit fertliser mix - provide food supply to roots.
3. use appropriate heater cable.
4. Use a mixture of fast and slow growing plants placed at the correct depth in your tank.
5. Use bogwood to provide both tier the tank and to produce tanins that seem both helpful to fish and plants.
6. I have 240 watts of light for 125 Gallons of water, at a maximum depth of 22 inches.
7. Use a spray bar from an external filter to help create a gaseous exvhange at the water surface.
8. THink carefully about the addition of CO2, I found it helpful to plants but not for my fish.

Hope this helps

Apisto

 

[G_Sharky]

What about a 25 W on a 33g tank, I currently purchase a couple of corkscrew and a Giant Hygrophilia, just wondering if i need to increase my lighting and how long should i keep my lights on?

 

[Lateral Line]

A_U:

I find Silver Sand packs down hard very quickly, swimming pool filter sand is better. I've used under tank heaters and Dennerle substrate cables and have never found either to make any difference.

With a spray bar agitating the surface, you will lose a lot of the benefit from CO2 injection as it comes out of solution very easily.

G_S:

Well....

>>>
Typically, 2 Watts per gallon is regarded as "Medium" light. For "High" you'd want 3.5 - 4 Watts per gallon
<<<

... so 33 gallons will need 2 x 33 = 66Watts for medium light. Should be running for 10-12 hours a day.