Need help with watering

Hi guys i have two 15 gallons pot indoor growing with 1000w hps, temp is 27-28 Celsius and humidity is 55%, right now plants are 60cm tall, i need an advice hhow much water should i give them, they grow in coco ,perlite and vermiculite mix 60/30/10 thanks for help

Your best best is to get a soil moisture meter, and when the moisture deep within the pot starts to get very low, give them a good drenching. Soil should be allowed to *almost* (but not quite) dry out between waterings.