[shinypenny]

So I'm fairly new to planted tanks, and have a non-standard shaped tank, so had a basic question. What lighting fixture would you recommend for a tank that is basically 36"x18"x24" (~65 gallons). It's tall (24") for it's gallon-size so I'm not sure how to adjust the lighting to compensate. Also, I am aware of the 3 watts per gallon rule often used, but that would need me to have the equivalent of 8 fluorescent bulbs (commonly 25 watts a piece for 36" bulbs)? It seems a little strange that I'd need a light fixture twice as big as anything I've found on the market designed for freshwater tanks.

Also, how on earth do I compare LEDs in all of this (clearly no wattage rule here). For the size of tank would I need the equivalent of a Marinelife single bright, double bright or plant specific system?

In case you're looking for further info, I was considering doing a mixed flourite/gravel substrate, weekly supplement dosing, and definitely NOT CO2. I'm prepared to limit my plants to hardier, lower light varieties to accommodate other things, like my wallet.

Essentially I would like to get more involved in plants, preferably without spending more on a lighting system than the rest of my tank/livestock combined.

 

[HD Blazingwolf]

3wpg is not effective rule
reflectors play a big role
the marineland double bright will not grow much at 24 inch of depth
i dunno much about led lighting other than my marineland single bright grows crypts and wisteria fine in a 10 gallon but i've since upgraded it with a 4th light strip i stickied in there. and im about to put a 5th as the smd led that go in there are very weak

 

[shinypenny]

I found this awesome link http://www.plantedtank.net/forums/lighting/105774-par-vs-distance-t5-t12-pc.html which does a great job of getting past the 3w/gallon garbage.

So based on that new info it looks like 2 T5HO bulbs would be enough to get me into the medium light range (50-100 PAR assuming not terrible reflectors).

From this other page (http://www.plantedtank.net/forums/diy/84212-designing-building-led-fixture-22.html#post1102937) it looks like the double bright would get me into the 50 PAR range at best when 24" off the substrate. I'm not exactly sure, but the design appears to put them 4" apart based on the case measurements and the number of rows of LEDs Marineland uses. Their plant specific product appears to push closer to 2" gaps, which would put it squarely in the 50-100 PAR range.

From this it looks like (if considering based on PAR only, allowing for setup variability) that the Marineland plant system ($430 for 36" model) is about equivalent to a decent two bulb T5HO setup (more like $120 here).

So I guess the one remaining question is, how much does the LED light being supposedly better help their cause? I did read this article (http://www.americanaquariumproducts.com/Aquarium_Lighting.html) which demonstrates that LEDs can be superior for growing chlorophyll to MH even if the PAR are identical. How much does that offset what I'm seeing above (A strong preference for T5HO)? Is it enough to make the 2 bulb T5HO comparable to the weaker LED (double bright?)

 

[shinypenny]

Wrote a long reply, lost connection, lost reply. Shorter version below.

I found this article (http://www.plantedtank.net/forums/lighting/105774-par-vs-distance-t5-t12-pc.html) which suggests that 2 T5HO bulbs at 24" could deliver medium lighting requirements, and that it's probably comparable at least in PAR values to the LED Marineland plant system. Seen as the T5HO is less than a third of the price, I'm leaning that way.

The only spanner in the works now is the effectiveness of comparing PAR on different lighting methods. This website with a study (http://www.americanaquariumproducts.com/Aquarium_Lighting.html) claims that LED are more effective than PAR would imply. However I'd be hard pressed to think that they were 3x more effective, which is what they would have to be to justify the price difference. If they are twice as good it's still cheaper for me to buy 2x T5HO systems.

 

[82nd_Airborne]

http://www.plantedtank.net/forums/lighting/105774-par-vs-distance-t5-t12-pc.html
Check out that sticky in the lighting section. It looks like to me if you mounted directly on the tank you'd need 1 T5 with a good reflector, but don't quote me on that. If you are interested in LEDs, there is a sticky for that as well.

 

[HybridHerp]

his tank is 24" high he said
he would need at least 2 t5ho onto of the tank to get medium light
to the OP, what kind of plants were you wanting to try?

 

[Hoppy]

Years ago the major problem facing planted tank keepers was getting enough light to grow plants. Today the major problem facing planted tank keepers is avoiding having way too much light, so algae become the major "crop" you grow.

A single T5HO bulb gives enough light at 24 inches distance (45-50 micromols of PAR) to grow any plants you will want. But, with an 18 inch front to back depth, a single bulb can't light up the whole substrate. You can get Catalina Aquarium to make a custom light fixture for you that uses two 36 inch T5HO bulbs, about 7.5 inches apart, in a 10 inch wide housing. That will give you good coverage of the whole substrate and 45-50 micromols of PAR. Just phone Catalina and ask for that custom fixture. They do it often enough for it to be routine.

 

[shinypenny]

to the OP, what kind of plants were you wanting to try?

I was just going to try a scattergun approach and was considering a basic low light multi pack like this one from live aquaria:
http://www.liveaquaria.com/product/prod_display.cfm?c=768+2146&pcatid=2146

I figured I could start there and then add based on my tastes once I've got some basic plants to grow.