Hi Hoppy, I am new to the forum and just posted a discussion for my planted 75 gallon, I have been having some problems with growth and was wondering if you would be able to take a look and provide me with some feedback on lighting? I hear you are the king of lighting planted tanks so any advice you can give me would be great!
T5 means 5/8 inch diameter tube, T8 means 8/8 inch diameter tube, T12 means 12/8 diameter tube, etc. HO means high output. T5HO are 5/8 inch diameter tube fluorescent bulbs, which use a ballast that drives them at about 1.5 times the wattage as T5NO (normal output) bulbs. So, a 48 inch T5HO is a 54 watt bulb, but a 48 inch T5NO bulb is about 38 watts, as I recall. The HO bulbs are designed to be driven at the high wattage, and the ballasts for them are designed to baby them as they start up, so the higher power doesn't shorten their life.
Power compacts, or what we usually refer to as PC bulbs, are the two parallel tube, but interconnected, usually 5/8 inch tube, fluorescents, that are operated at a lower wattage per foot of bulb than T5HO bulbs are. In the UK I think they refer to the spiral screw-in bulbs as power compacts but I'm not sure. PC bulbs, in our usage of the term, have 4 contacts on the plug-in end, either in a straight line, or arranged in a square pattern. But, as far as I know we use them with a single power wire to each pair of contacts, so I don't know why they have three contacts.
Osmocote is used as a very thin layer, a dusting, under all of the substrate. I should then slowly release the fertilizers so the substrate has a continuing supply of them, until it finally runs out. Laterite is a form of clay, which has high CEC, and has lots of iron in it, which may or may not be very available to the plant roots. Mulm is a good source of good bacteria, which will more quickly establish the bacteria colonies in the substrate, and those colonies, as I understand it, convert the iron in clays to a more usable form for the plants.
A single T5HO bulb, with the typical single bulb, highly polished aluminum reflector, provides about 40 micromols of PAR at 24 inches from the bulb. Since your tank is 24 inches front to back, three bulbs spaced evenly across the top should give you about 60-70 micromols at the substrate, dropping a bit at the front and back glass. This would be about medium light intensity. Or, with 2 bulb fixtures, two of them - 4 bulbs total - with the two fixtures about 8 inches apart should give you at least 100 micromols of PAR at the substrate level, which would be high light intensity.
The best source of fast growing plants, stem plants, is a local aquarium club, Sacrament Aquatic Plant Society, for example. I think you joined? If not, visit http://groups.yahoo.com/group/sacaquaticplant/ and join us, then send out a group email asking for plants. That usually gets you free cuttings, but only from the stem plants currently being grown in the group. The next best source is the Swap n Shop forum here.