Thanks for all the comments. Doing a "column tank" like this is forcing me to think of my layout far more 'three dimensionally' than ever before due to the fairly extreme dimensions of the tank I'm considering.
The tank I mentioned in the opening post is made by Top-Fin, which is pretty obscure, PetsMart affiliated...seem to be made by Perfecto. Anyways, according to this
, the 47g is 20x18x30 and they have a 37g which is 20x18x24.
Im not so sure you will like the results with 36 watters. The crypts and ferns should be fine but that is a lot of depth for the mosses if you plan on it growing down low in the tank, especially the fissidens.
I was planning on putting the fissidens and taiwan on the driftwood. On the bottom "down low" would be some windelov java, wendtii crypts, and 'micro' e. tenellus.
Im not so sure you will like the results with 36 watters. ..Lets face it, a 96w aint fitting over that tank nicely. Throw out the wpg assumption on this tank...
The WPG rule is worse than worthless, it's misleading. That said, 3x36w will easily fit over this tank - many people put 2x36w on 10g, which is 20"x10" surface area, and this tank is 20"x18" - so no worries there on it physically fitting on top or anything. I believe even 4x36w will fit according to this
. Coralife makes a 20" 96w fixture, but their "reflectors" are incredibly lame. 3x36w AHS = 108w, and they are quality watts with individual reflectors and better coverage. The question is: will the intensity be enough down low? I don't know, I've never dealt with depths like 30." More generally, should I countenance Rex's self-proclaimed 'rant'?:
"I have seen a lot of people repeating the lie that deeper tanks need more light. That might be true if you are using crappy lighting systems or barely have enough light as it is. But if you use decent lighting systems with decent reflectors the depth of the tank doesn't mean squat. You might hear about spectral drop off or lighting decrease. Bull[censored][censored][censored][censored]! If your tank was 30 feet deep it would be one thing. But the difference between 18” and 30” is not enough to worry about as long as you have good reflectors."
Thanks, LeftC, for posting that thread. He was having trouble getting glosso to grow horizontal w/130 Coralife watts over what looks like the 37g, 24" deep tank mentioned above. Note that his glosso was still growing, just not up. I'm not planning on glosso or anything. Just chain sword and crypts and java fern and such. I'll stick my neck out and say that 108 AHS watts are more than 130 Coralife watts (currently owning both), but the tank I'm considering is 6" deeper....
Pendant MH's are the lighting of choice for deep tanks just due to the high wattage vs the physical size of the fixture. L
Lighting is key though, under power it and the plants will be stringy looking.
I'll admit I'm a total noob to MH, but thanks, I'll look into them. The price tags are pretty intimidating, but I'm excited about this layout and will do whatever is necessary (within reason). If anyone has any general info on MH lighting for planted tanks, or can weigh in on the purported 'depth myth', I'd really appreciate it.
I've given a bit more thought to stocking. This is reflected in the opening post above.