So my LFS has tons of plants. They are listed as Low, Medium, and High Light plants. I know it's impossible for you to know for sure without specific plant names..but any advice on what those mean?

I have a 75 gallon tank (48" long) with 2x32 watt bulbs. It's one of those shop lights from Home Depot. One of the bulbs is actinic (blue-ish color). So that's almost 1 watt/gallon. I really dont want any more wattage than that b/c I don't want to have to deal with co2 or anything like that.

So do you think I can get away with the plants they have listed as medium light, or am I stuck with their low-light ones (eg Java ferns, subulata)?

You need to change out the actinic bulb...it will do very little for your plants and may promote some algae growth. I would say that you are stuck with mostly low light plants. If you changed to some 40W 6500k bulbs you may be able to grow more. It is funny that you mention CO2, I think that if you were to add it with your low light you'd be able to get many more plants to grow under your light.

Light in a planted tank is a very tricky subject. Plants really only benefit from light in the lower 2/3 of the visible spectrum (bulbs of 10,000K ratings or lower). Actinics are in the upper range (16,000K if my memory serves), so the plants aren't able to fully utilize all of the actinic light in photosynthesis. I would suggest two 6700K bulbs.

The ultimate test of what light you have is to use a PAR meter in your tank at the substrate level. PAR meters are hard to come by, however (I have to settle for a Lux meter and conversion factors). In general, with shop lighting, 1-2 WPG is low light, 3-4 is medium, and 5+ is high light. The higher the light level, without injected CO2, your tank will just become a giant algae vat. With CO2, you need to baby the system to get the right results.

If I were you and I was interested in the medium and high light plants, I would drop a little cash on Craigslist and get myself a nice T5HO fixture. They are fluorescent but are much higher quality and efficiency. With T5's, the WPG rule no longer applies and you will have to base your results on plant growth, algae growth, or the implementation of a light meter.

Just my overly-complicated and ridiculously nerdy thoughts...

Sources:
PAR vs Distance, T5, T12, PC - New Chart

http://www.hallman.org/plant/huebert.html

Basics to starting a Planted Tank - The Planted Tank

Aquarium Lighting; Reef, Planted Light Information. PAR, Bulb, Watt, Kelvin, Nanometers, MH, LED.

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Officially fishless until after the move....tune in later for details!

Hello b...

I keep low to medium light plants in my 55 G tanks and have a single bulb in each. I use either a 48 inch, T8, 32 watt, 6500 K bulb in the taller tanks or a 48 inch, T12, 6500 K bulb in the wider tanks.

Low light is up to 1 watt of light per gallon of tank volume. Moderate light is 2 watts per gallon, strong light is 2 to 3 watts per and anything over 3 watts is bright light. This is "old school' info., but it works for my tanks.

I have at least a dozen different plants I grow. Some are planted in the gravel, some are potted and some are floating to take full advantage of the lighting.

A couple of 48 inch, 6500 K, T12s will work fine in your 75 G if you have a strip to accomodate two bulbs.

GE has a great, aquarium plant bulb for about $10.00 at the local hardware store. I have them in my tanks and they last about 10 months before they need to be replaced.

There's really no reason to have expensive lighting if you keep low to moderate light plants.

Nicely planted tanks are very simple. Just match the plant to the lighting you have, change half the tank water and dose a good fert weekly and you're "good to go".

As always, just an old, humble, waterkeeper's opinion.

B

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Low Tech Water Building Keeper

Perhaps I should read all the other responses so forgive if I appear to be repeating.

On a 75g I would use 2 of the home depot shop lights with 6500K tubes. Home depot (last year or so) had some 5500k tubes and Lowes has some GE tubes at 6500k. both in the price range of 2 tubes for $6 or so. Lowes had a 10 pack for $22 or so. $2.2 per tube is great, you could share and would have enough tubes for the next decade.

With that lighting you could grow just about any plants in your tank. With no co2.

(I use anacharis/vals, small potted (crypts, small swords) and a few amazon swords. I have als used micro swords, wieteria, various Java (but prefer the "plants" not the moss type Java).

my .02

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fw leiden since 1979, fo salt since 1979, mixed reef 55g 2002-2009. Strong emphasis on the tank taking care of itself. Balanced with plant life, no water changes, tap water, no filters in FW. Only dosing calcium, alk, mag in marine reef tanks. http://www.aquariumforum.com/f15/my-...ods-26410.html
recent tanks (till 2009) 7 years- 10g FW leiden 7 yrs, 55g mixed reef 7, 2 yrs, 20g FW leiden, 10 g fw leiden , 29g mixed reef, current tank 55g leiden

So youre saying 4 total? I have one shoplight with two bulbs now

I know you say you don't want CO2....but, there is a thread on one of the other forums where a guy is showing his tank full of typically difficult to grow plants or thought to have a lot of requiremnts to do so, yet doing it all with 80W of T12. The tank is pretty incredible. He has it with pressurized CO2 though. The CO2 will allow higher light requirement plants to grow in lower light tanks. He really shows what value CO2 can have. The best thing is that the lower light you go, the less your tank parameters have to be so spot on for everything to work well without algae showing up.

Yep

just add another shop light for the 4 tubes total. ~120w.

U should be good ta go with that.

my .02

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fw leiden since 1979, fo salt since 1979, mixed reef 55g 2002-2009. Strong emphasis on the tank taking care of itself. Balanced with plant life, no water changes, tap water, no filters in FW. Only dosing calcium, alk, mag in marine reef tanks. http://www.aquariumforum.com/f15/my-...ods-26410.html
recent tanks (till 2009) 7 years- 10g FW leiden 7 yrs, 55g mixed reef 7, 2 yrs, 20g FW leiden, 10 g fw leiden , 29g mixed reef, current tank 55g leiden

Algae concerns at that wattage? CO2?

Yep

But usually less of a problem then with high wattages.

Actually thinking about it if you could get a third fixture over the tank that would be 2 watts/gallon and a good number.


my .02

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fw leiden since 1979, fo salt since 1979, mixed reef 55g 2002-2009. Strong emphasis on the tank taking care of itself. Balanced with plant life, no water changes, tap water, no filters in FW. Only dosing calcium, alk, mag in marine reef tanks. http://www.aquariumforum.com/f15/my-...ods-26410.html
recent tanks (till 2009) 7 years- 10g FW leiden 7 yrs, 55g mixed reef 7, 2 yrs, 20g FW leiden, 10 g fw leiden , 29g mixed reef, current tank 55g leiden