Rust spots on leaves. 5th week flower

Hello

My plant is about 40 days into flowering. The new growth have rust spots showing up, it started from the bottom, and its worked its way up to the top of the fan leaves.

Its in 3 gallon FFOF, 600W HPS. 74f on/66f off. I water with GH nutes every 3 days or so. I believe this is calcium deficient or pH issue, but I am not sure. Any ideas would be appreciated.

well is there any mites under the leaves? I does look like a cal issue https://www.icmag.com/ic/showthread.php?t=231387

https://www.icmag.com/ic/showthread.php?t=11688 check out these threads, might help out??

IMO- calcium deficiency.

check your pH.

Good Luck on Your Grow.

Get a TDS/EC meter and measure your source water and nutrient water. Get a ph tester and measure your soil ph, source water ph, and nutrient ph. With this information you'll know a lot more about what you are doing.

try to get some pics that arent so orange/red cant really see shit by those pics