From reading the posts on this and other forums the general consensus is farly consistant if you are planning a live planted tank ( which i am ) you need a number of things, but most important is Lighting
Lighting is not the most important. You can grow under virtually any light. No necessity to get to a figure. The light however determines what you need to do to facilitate the growth the light pushes the plants at.
The guidelines most seem to agree on are the following:
For a Light to medium planted tanks you need to achive a minimum of 2wpg
Substrate should be an approx 1cm layer of sand maintained via proper selection of tank inhabatants
lower substrate should be a flourite or laturite material.
Supplemntal Co2 will be needed and can be done via DIY means or commercial made equipment.
Maybe a bad use of words but noone 'agrees' on any of the above, in fact some of it is just personal choice!!!
Noone agrees on light anyway and a minimum 2WPG is not needed for a light to medium level. Light can be as little as 0.5WPG T8 up to 1.5WPG T8. 2WPG T8 is medium to high IMO as this is the sort of level where you HAVE to use pressurised CO2 to be able to maintain a stable supply.
The CO2 is correct but noone ever listens. You tell them they need pressurised and they say OK and then ignore you and try to go with DIY on too large a tank or with too much light. If they did listen this forum would be so much easier. CO2 IS the most important thing in the tank and the hardest to get right so if you can't get it right with the DIY its go pressurised or fail. very simple.
You are trying to get too in depth for light. Don't assume you need a certain level. Forget the length of the tank and think of the volume of water. The length means nothing. The water volume and height is much much more important. Forget watts and Lux as a measurement of light. If you want to get technical you need to measure PAR!!!! Don't think 1W=1W because that is not what the WPG rule is about. It was calculated on how much light gets to the substrate of an average 20-40USG tank using T12 lights with reflectors. Do you have an average 20-40USG tank with T12s? I doubt it.
T5s will be virtually double the mount of light getting to the substrate as a T12 due to their higher efficiencies and less restrike so you can virtually say 1W on the WPG rule = 2WPG if using T5s!!!
So in answer to your question on light.
Decide what you want from your tank. Do you want to get scapes grown, photgraphed, and start on the next every few months or are you after a more permanent planted setup. Do you want to have to maintain the tank a lot or just a little, Do you want to go pressurised or not.
Decide what you want form the setup and then get the equipment to match the requirement. Don't get what people 'say' is a guideline and then decide because once you buy someone else's guideline setup you are forced down a certain avenue. Decide what you want and then get the applicable lighting, filtration, CO2 etc.
Any more question?
AC
LOL well said !
More questions !!! Oh Yes, many as yet, upon awaking this AM i guess you could say i had an epiphany of sorts, suddenly i understood ( or at least think i do) the lighting question, which now to me sounds even more confusing than when i asked it.
I do understand and agree from what you wrote, the wattage has really nothing to do with it other than maybe as an overly simple general unit of measurement.
Let me see if i now am closer to what is truely meant or needed.
If for a particular set up you wish to attain a "Lighting level" of 2wpg in a 55g tank 48" in length ( and assumeing 10% loss in volume to substrate and other displacements) no more than say 21" distance from light to substrate, you would need 100w of effective radiated light over the
length of the tank.
this can be attained a number of ways, the most effecient ( remember these are all assumptions) would be a 48" fixture as the light output for the given wattage is now over the length of the tank. If instead you set up using 24" fixtures you would now need twice the wattage to "cover" the same area.
In short the WPG desired should be assumed to be as tank coverage as opposed to fixture power consumption?
Am i now a tad closer? or at least on the proper track?
and all the above is assumed seperate of bulb design or package, IE while a T5 will rate higher in wattage it is a smaller package and as such radiate out over a narrower area, providing less
"light area" coverage for the plants, T12's being larger but typically lower in wattage will radiate over a larger
"Light area" just with less "light". It seems to me a more accurate method of determining lighting needs is "LUX" this then raises the queston what is the effective drop of LUX per inch ( or some other measurement ) of water, and yes i understand clarity will factor into this.
BTW WHAT IS PAR???
This all brings it somewhat full circle into desired plantings, so what truly is meant by medium light requiremements for certian plant species.
I am not looking to set up a plant farm, I am more looking to set up a natural looking live planted tank, that will
NOT require near constant attention.
Lighting to be just enough to assure suffecient Photosynthsis for the plants to grow well ( not looking to farm them as i said), and make the fish look good, oh yeah, and not need some expensive Co2 pressure injection system.
What i guess i still fail to totaly understand is WHAT is "medium light" requirements for the plants? and who determins that short of the hobbiests who have successfully growen and or maintained them.
Again correct me if i am wrong here, these are my current understandings:
(Using the above example)
For any given species of plant if you desire rapid propagation then increase ferts,Co2, and increase Lighting to >
( insert method of measurement here) over the plant growth area
Co2 requirements increase as more "Light" is applied (more accuratly i guess is "as photosynthesis is increased")
as you also pointed out, I am also not looking to simply "Parrot" someones setup, because their setup is not going to be like my setup or not looking to duplicate someone elses work, although i am also not looking to duplicate someone elses work at determining what "MY" lighting needs are.
This hobby has been around too long for anyone to have to get into some long study of plant lighting requirements.
Someone has done this already, if their methods are sound and other hobbists agree, then it should work and be useful information to those that come after ( " ME " ). Now then the question is....... Where is this information ? ? ?
and bear with me here, i am just trying to re-learn, these new systems are all new to me, i still have not gotten used to the fact most everyone changes out 25%+ of their water every week in Tropical tanks.
Used to do that in a marine tank, but seldom if ever in my tropicals, of course i also understand no one uses carbon much at all anymore either, but that is a subject for a differant post, and a differant area.
Thanks in advance