Re: Eco-Complete by itself, or as a cap?
I have limited experience, but from some of the reading I have done 75 par is pushing high light. You might be asking for algae trouble if you aren't using co2.
I've been using Eco only with great results for awhile now (4 years). Be sure to supplement with root tabs as needed for root feeding plants.
You are most likely going to need CO2 with that fixture mounted as designed. They have excellent reflectors.
Hmm. I guess I could get another light fixture ... That one seemed petty straight forward and looked nice. I also liked how it could link up to more eventually. I had read elsewhere on here that a low tech setup had success running the light for like four or five hours on the morning and again for four or five at night ...
I am tempted to look into CO2 setups, to be honest ... But was going to wait until I had some early success. Heh.