New xr15 g5 pro light help for 20g

[Mark75g]

So have a 20 g Nuvo that I am doing some chalices and zoas in. Had 2 FluvalSmart led on the tank and just switch to the new xr15. Currently running the lps/zoa setting and on 50%. Started at 40% couple weeks ago.
Not sure what % intensity I should run at. I have zoa frags in my main tank under 250 watt 14k metal halide and they are doing great. I don’t really have access to a par meter

 

[zukihara]

I would suggest you check on the BRS video on the XR15 and try to relate their par measurements with the dimensions of your tank. I think that would give you some idea at least.