HELP!!! PLEASE SEE PICS

My plants has been flowering for 3 weeks now and I have been having some issues with the leave turning yellow and brown and they tend to fall off. This has been going on for 1 and a half weeks.

Grow medium: happy frog soil
Watering: every 3 days with tap water
fertilizer: Tiger bloom 2 teaspoons per gallon every other watering. I just started Bigbloom yesterday using 4 tablespoons per gallon every other watering
temperature: 86 F outdoors living right next to the ocean.
light schedule 12 hours
Humidity is 60-70%

I do not have a ph meter to check the Ph because I live on a small island and they do not have them for sale here. The water here is treat with Chlorine and is pretty hard. What do you think the issue is, could it be magnesium/ calcium deficiency? Do you think foliar feeding will help, maybe the PH is to acidic?

Please help

It could be the tap water. You can get a ph pen online and have it mailed to you.

Ocean spray could be affecting them.. if they are right next to the ocean they could be getting misted with saltwater.

get a PH and a TDS meter very cheap on amazon, I bought both for under 25.00,use distilled water for now