T5 or CF for 75-gallon natives?

I'm completely new at this. I've been lighting my 75 with 2x40W fluorescents, which is woefully inadequate. My plants are almost all native from marginal habitats here in South Carolina, and they need high light. Nearly all would grow wild in less than 2 feet of water in otherwise direct sun, and I now have them 2 feet deep in a room with essentially no sunlight.

In the current lighting the only long term survivors have been some ceratophyllum, valliseneria and anacharis, plus a couple emergent species that have put leaves above the surface, and a bit of java moss I couldn't resist. The val isn't doing very well, and I have some other plants I'd like to use but they just keep dying.

I'm looking at a couple options, but I know very little about it. Choices I am considering:

http://www.catalinaa...roducts_id=1423

http://www.drsfoster...fm?pcatid=13733 (the 48" one)

http://www.drsfoster...fm?pcatid=16770

light may not be your problem, (you have slightly better than 1 watt per gal)

I would look at nutrients, do you have a soil underlay? are you injecting co2?

plants need more than water to grow

Have you followed this thread : http://forum.nanfa.o...?showtopic=6489

The tank dimensions are basically the same, yours is just not as tall.

T-5's seem to work way better for plants than CF's. It's definately been my experience.

What are you trying to grow that you are having trouble with?

I do not have any soil in the substrate, just sand and gravel (1/3 of the tank is sand and 2/3 gravel). I am not currently supplementing CO2 but planned to add that at the same time as upgrading the light. I have been using fertilizers (a micronutrient one with Fe/S/B/Mn/Mo/Zn/Cu and macronutrients separately as needed) but haven't noticed any effect when I use them or don't. Nitrate is consistently around 20ppm. I don't have a test for P or K. Most people on the tropical forums seem to think that isn't necessary - as long as the source of N is primarily fish food the others should be reasonably in balance. Any differing opinions on that?

I had been following the 90-gallon thread, but it doesn't really seem to answer my questions. It may be that I'm just missing some essential background information. There seem to be a lot of people saying they use one brand or other and like it, but nobody really explaining why.

Pretty much every leafy plant I've tried has been a failure. I did get some Ludwigia to grow, but it just grew really fast up to the surface, and then along it, so I ended up with a thin stem going up through the tank and a giant wad of crap floating on top, from which the leaves would continually die and drop garbage into the water. Smaller foreground plants with broad leaves just fall apart.

The reason I think light is the culprit is that the same plants seem to do fine when floated in the same tank.

I do not have any soil in the substrate, just sand and gravel (1/3 of the tank is sand and 2/3 gravel). I am not currently supplementing CO2 but planned to add that at the same time as upgrading the light. I have been using fertilizers (a micronutrient one with Fe/S/B/Mn/Mo/Zn/Cu and macronutrients separately as needed) but haven't noticed any effect when I use them or don't. Nitrate is consistently around 20ppm. I don't have a test for P or K. Most people on the tropical forums seem to think that isn't necessary - as long as the source of N is primarily fish food the others should be reasonably in balance. Any differing opinions on that?

I had been following the 90-gallon thread, but it doesn't really seem to answer my questions. It may be that I'm just missing some essential background information. There seem to be a lot of people saying they use one brand or other and like it, but nobody really explaining why.

Pretty much every leafy plant I've tried has been a failure. I did get some Ludwigia to grow, but it just grew really fast up to the surface, and then along it, so I ended up with a thin stem going up through the tank and a giant wad of crap floating on top, from which the leaves would continually die and drop garbage into the water. Smaller foreground plants with broad leaves just fall apart.

The reason I think light is the culprit is that the same plants seem to do fine when floated in the same tank.

I am using 260W Oddyssea PC light fixture, The light penetrates through the gravel then about a 1/2 in into the soil from what I can see. it holds 4 65 watt PC, I still have one actinic bulb that is getting replaced as soon as the bulb arrives. This light fixture can be purchased on ebay for roughly 100 NEW, I bought mine used for $55. I am not sure if it is the best light fixture but it works. The ligths are rather expensive if purchased at local LFS and chain stores $45 to $50 but I found them online for $12 each. even with shipping I am paying less than half the price locally.

Hi gzeiger,

I agree with you that your light intensity probably has a lot to do with it. My suggestion would be to add another bulb or overdrive the bulbs. Or I would try the third product you listed - that one seems interesting to me.

Regarding your substrate - when you say sand and gravel, what kind of gravel are you using? Pea Gravel is too large if soil isn't used. Small gravel (about 2 mm diameter) can work OK for some plants, especially if it isn't cleaned and mulm can accumulate.

Don't add CO2. It won't do anything until you can get better growth. All it does is speed up growth when other conditions are right. In my opinion, I don't want it speeded up that much because it makes for more maintenance. But some people like to tinker and make the plants grow like gangbusters. It's all personal preference. But it won't help at all unless the other conditions are growing healthy plants.