Watts per gallon rule rock solid?

[zombie2k]

Hi again guys, I've got another noobish question--this one regarding lighting.

Until now I relied on the opinion of the LFS guy, who said two 15 watt powerglo lamps with fluorite would make my plants grow astoundingly in my 30 gallon tank--but so far im not so sure that is the case.

I have anubias, anacharis, java fern, jungle val, and some plant with leaves that have a purple underside.

It seems that only the anacharis and anubias are doing decently tho growing slowly imo. The jungle val, which I suspected my redtail shark of chomping on before i gave him back to the lfs seems to be withering away. Some untouched leaves at the bottum look like they are turning brown and some of the other leaves seem to have become thin.

Is my lighting really that inadequate or do I perhaps need some kind of co2 system? My filter creates quite a bit of surface agitation, if that may be the problem i can point it toward the glass so it creates less.

I just recently read the watt/gallon rule which is 2 watts per gallon--I only currently have 1 it seems. I didn't notice any higher watt bulbs for my size fixture at the store (18" t8). Did I waste 36 bucks on useless lamps or is it another problem and how can I fix it without breaking the bank?

 

[rich311k]

You have enough light for most of your plants. You may not have enough light for the vals. At 1 wpg CO2 is not needed but it always help. The plant with the purple leaves is probably a non aquatic plant, you should remove it before it rots.

Changing bulbs will not effect the wattage. You need another fixture in order to increase the light. If you stick with the anubias, ferns, and anacharis you have enough light.

I am moving this thread to the planted section.

 

[Jchillin]

There is a bit more than just the rule. What may be happening is you may not have a decent K rating on those bulbs.

That aside, the other issue is nutrients. The symptoms you describe could be due to a lack or deficiency of nitrates and/or potassium. What is your current level of NO3?

 

[Purrbox]

The Watts Per Gallon "Rule" is more of a guideline than a rule. It's based on a specific range of tank sizes (about 55-75 gallon) using T12 Fluorescent Lights (1.5" diameter bulbs). If you tank falls too far outside the size range or you use more efficient bulbs, then this can really make figuring out how much light you need interesting. Further, the efficiency of your reflector, the height of the fixture above the water, and whether or not you use a glass canopy will all affect how much light actually gets into the aquarium. Then add in that the spectrum of your bulb plays a part in how much light the plants can use of what actually makes it to them, and that this spectrum will shift as the bulb ages and you start to see how tricky estimating light can become.

All that said, you should have enough light for most of your plants as both Bill and Rich have mentioned. Just make sure to avoid plants that aren't true aquatics and ones that need more light than you can provide. You're not going to see significant growth with that amount of light, but then again you also won't have to do as much maintance on the tank either since you wont have to worry about dosing as much fertilizer or trimming your plants frequently.

 

[zombie2k]

I was hoping for significant growth though, I'll just have to wait a bit longer or buy a new hood /shakes fist at eclipse system

The bulbs say they are 18,000K but I've read elsewhere that they are actually lower.

Will take that purple belley plant out, thanks for the help guys!

 

[Purrbox]

Generally it's recommended that you aim for a bulb that is a Daylight bulb and has a Kelvin rating between 5000-10000. The Kelvin rating doesn't have a lot of effect on the plants, but rather how the aquarium appears to the human eye.

To get the faster growth you're looking for you're going to need to upgrade your light fixture. This would involve adding additional fixture(s), replacing the existing fixture, or ODNO the existing fixture (replacing the balast to run more power throught the bulbs).

Adding CO2 could help as well, although it sounds as if you'd need adjust the water flow in the aquarium to decrease the amount of surface turbulance. Otherwise you'll end up just gasing off all the CO2 you're working so hard to inject.

After addressing both lighting and CO2, you'll likely have to start dosing ferts as well. If you haven't already, I'd suggest reading through all the linked articles and threads in the Read This First Sticky at the top of the Forum.

 

[jsoong]

Powerglo light ---- that is low voltage INCANDESCENT pond light by Languna??

If so, that is grossly inadaquate. The WPG refers to NO flourescent light. 30 W of incandescent has the output of about 7 or 8 W of flourescent.

 

[zombie2k]

these are what I have in particular

http://www.hagen.com/usa/aquatic/product.cfm?CAT=1&SUBCAT=112&PROD_ID=01016250020101

 

[jsoong]

Those are T8 flourescent, so you are good! T8's are about 1.25x more efficient than T12's, so you would be in the 1 to 1.25 WPG range - OK for what you have.

<Hates it when they use the same name for totally different class of light! The Powerglo name is also used in their pond halogen light line .... good for seeing so I don't fall into the pond at night, but useless for growing!>

 

[Purrbox]

When you need to buy bulbs again, you're much better off getting the bulbs from your hardware store. They are a lot less expensive and generally just as good if not better than the aquarium specific bulbs.