The friendliest place on the web for anyone with an interest in aquariums or fish keeping!
If you have answers, please help by responding to the unanswered posts.
There are two good choices, El or PPS-Pro. I dose PPS-Pro as it allows me to custom dose to the needs of my tanks. Since I use a lot of non green plants and have very high lighting (metal halides & T5HO's) in my 220g I run low nitrate (10ppm) and high phosphate (5-10ppm) to bring out the best color in my non green plants. Here's a link if you want to check out the color I achieve in my tanks.... Aquarium Advice - Aquarium Forum Community - Rivercats's Albums.
Here's a good thread to read about PPS-Pro dosing. Only read the opening post not all the comments after.... Newbie Guide to PPS-Pro - PPS Analysis and Feedback - Aquatic Plant Central. The only thing I do different than what it says is that I use 3 dosing bottles and separate my nitrates into their own bottle, phosphates and potassium into another bottle, and the micro's in the 3rd bottle. The recipe also calls for using MgSO4, magnesium, which if your GH is 4 or above or you have hard tap water you really don't need to use it in the mix.