My equipment, and improvements as well as reactor questions

[Buddy08]

I decided I would register with RC and see what you experts had to offer as far as advice is concerned. I have a few questions about reactors and such. I'm putting forth the effort to finely tweak my 75g reef for the better as I would like to start keeping anemones, clams, and sps's... The tank is roughly 8mos old now.

What I am currently working with a 75g and 125+ lbs of live rock. It has 2x 1" drilled bulkhead overflows in the top right corner, draining into a 20g Long sump with a 5g fuge. In the sump, I have my visi stealth heater, and my protein skimmer. Im using a mag 7 as my return pump pushing through a 1" pipe back to the tank. I currently have 2x maxijet 1200's in the tank with sure flow mods. Above my tank in my custom built canopy, I have 4x 48" 54watt t5 bulbs with reflectors pushed by an aro vho ballast. Thats basically my setup. As for livestock, I currently have a few softies, lps's and fish but again would like to start keeping sps's, nems, and clams.

I am replacing my lights within the next few weeks with DIY LED's from RapidLed so I can assume I will have the light required to keep what I want to but with that being said, I want to focus more on my equipment to better increase my chances. Only concern I will have with my LED's is that my canopy is only 12 inches tall and only 10 of those inches would be considered above water level as the other 2 meet flush with the glass on the display tank covering its plastic brace. Subtract the required inches for the heat sinks, fans, and optics and I may be hanging $600 dollars of equipment 6 to 8 inches above the water.

My water parameters are as followed:

Ph 8.2
alk 9dkh
calc 440
nitrates 0
nitrites 0
phosphates 0 (although I see a few cyano spots coming up on rocks, not sure if its my lights or water)
I have yet to test my mag levels due to BRS being sold out every time I go to purchase a kit but as soon as they restock, I will be purchasing their two part dosing system and a salifert magnesium test kit to ensure my water is in check and ready for the sps demands.

I would like to improve my equipment. Again, I will be replacing my lights. If you all think those LED's being that close to the water is a bad thing, I may just add 2 more T5's brining it to a total of 6x. I also want to replace my powerheads. Which would you recommend and how much flow?
Once I order my two part dosing kit from BRS, I have considered possibly ordering dosing pumps as well. Are they necessary? And how many should I order. Lastly, I have been looking at some reactors but honestly from retail web pages, I cant tell the difference between GFO, Carbon, Phosban, and bio pellet reactors. What do each of these do? Which would you recommend for my tank setup? And what media should I use with whichever you recommend.

Sorry, I know this is a lot to ask in one post but thought I would get it all out there.

[Buddy08]

anyone?