I'm about 10" above with my sol blues. Running in the 50s with my white on ramp up and 60s on blues on ramp up. I believe AI Sols have narrower optics so percentages are usually run lower than hydras.
its hard to really tell because I tried the hydras about 15 inches off the water and only a 12 inch tall frag tank 40 60 100 % 40 we barely got 110 par at 60 % we got barley 120 par and at a 100 % at the bottom of the tank 12 inches deep 150 par barley lol so I recommend you get a par meter and test we spoke to the company and they told they do not test in water even though on their website it says it was measured in 24 inches of depth im not saying they are bad lights but I feel not represented honestly by the company
this is why i love this hobby, so many different opinions...
sounds like i am going to have to just find out for myself
i am running them 9" off the water and sunrise 11a sunset 7p-ramp 2
so far corals doing pretty good, good pe on sps