So here is my story:
I'm pretty new to the hobby, started my 29 gallon planted aquarium less than 2 weeks ago. Its been a few days since my first planting and stuff is definitely growing!
Here is my setup.
Light : 2 x 24 Watts Zoo-Med Aquasun T5HO about 20-22 inches above the substrate. According to the PAR data, this puts me at "high" light, but considering the poor quality of my reflector, I am under the assumption that this is actually "medium" light.
I don't know if anyone has measured the PAR from that light. If not, you are probably in the best position to judge how good the reflectors are. No reflectors would cut the PAR to about a third of what good reflectors give.
Co2 : I am planning to dose Excel. Trying to avoid a pressurized co2 system if at all possible, cost is not the issue. It is for purely aesthetic reasons as I don't want any extra equipment around my aquarium.
Excel is OK for low light, but isn't nearly as effective as CO2. You might get by with Excel for medium light, but you might not.
Substrate : 2 bags of Eco-complete Red mixed with a bag of fluorite. Mixed for color variation and no other reason.
Nutrients: I'm currently only using Seachem's flourish, which covers most of my micros.
Unless you have low light and some nutrients in the substrate, like substrate tabs, you need to dose NPK - not much, but some.
My temperatures are generally around 79 F, PH at around 7-7.5.
My Bioload is as follows:
1 Pearl Gourami
6 Kuhli Loaches
4 Yo-Yo Loaches
1. Do I have too much light for an excel only setup?
2. I am aware of the macro nutrients - Nitrogen, Phosphorous, and Potassium. I know I will probably have to inject some K, but are Nitrogen and Phosphorous necessary given my bioload and the available nitrates?
3. Is there an obvious algae situation here?
I see a lot of people dose dry ferts almost indiscriminately, and I am wondering if I should follow this strategy. My big thing is having to do a 50% water change every week, I would prefer to keep it at 20-25% max.
I don't believe anyone posting here doses ferts indiscriminately. A lot of us dose secure in the knowledge that having 2 or 3 times as much of a nutrient as is needed by the plants is doing no harm, so we don't sweat it. Others, like you, who don't want to do 50% water changes, dose more lightly, adjusting the dosages by watching the plants carefully to be sure they aren't being limited by the absence of some nutrients. Those folks can do smaller water changes, less often.
I guess my goal here is to create a balance between fish waste and plant consumption. Where nitrates/phosphorous from bio waste slowly rise and are taken up by the plants, thus creating an equilibrium, with as little outside (carbon/water/potassium are almost unavoidable) help as possible.
Many people have tried to create that equilibrium, but few are successful unless they stick with low light. Even then, it won't work without starting with a nutrient loaded substrate, so the plants can always get their needed nutrients through the roots. The best efforts at doing this equilibrium type of tank are the "el natural" tanks, done per the Walstad method.