Input Wanted-How many plants approx under 600w hps preying mantis light.

Hi can anyone give me bit of info, I got a 600w hps dual spectrum bulb with adjustable preying mantis light with all wall diamond mylar. I have grown 10 plants under it but was wondering how many i could put in there and if anyone else uses 600w hps and how many they grow. I use indica based strains, 7 to 9 weeks flowering and veg between 3 and 4 weeks. Had good results in past but want to put more plants in there but so there comfy in there not crowded or not getting enough light. :rasta: