Reef controller!
Get an extension card from rapidled(5v pwm to 0-10v dimming) and install a reef controller firmware to the arduino. Maybe you can download the code somewhere, I believe I have seen a download link somewhere on stevesleds website. It might also be worthwhile to search through appropriate forums.
I know that you can buy finished copies of the storm controller on chinese platforms(alibaba, ...) as well.
I also believe VegasWinners gogreen controller is based on Arduino too. Maybe he could allow you to use his code.
There is also a guy on ledgardeners forum who developed his own controller( project Kiasmos ). Main things like UI are already done but the project is not finished yet. He just realized that he needs to convert 5v pwm into something a HLG driver can use for dimming but the rest is almost done. He is a smart guy, could be interesting...
I was too lazy to create an account. If you do, take the tip with the 5v pwm to 0-10v extension card, so you can move on and complete the project soon.
https://ledgardener.com/forum/viewtopic.php?f=27&t=742
https://trello.com/b/Df2TfWFe/developping