so hopefully Al or Josh or someone with a good handle on chemistry can give me a hand here--

i'm in san francisco, really good clean water with low TDS and salts, but pH is high, typically about 8.5 or so. i've got dozens of plants, most of them in either gritty or some semblance of a 5-1-1 to 3-1-1 type mix. tomatoes, cane berries, blueberries, peppers, citrus, herbs, grapes, avocados, strawberries, flor de jamaica, etc.

i adjust my fertigation to shoot for a pH of roughly 6. i acidify with white vinegar added to my mix of foliage pro, protekt and maybe some of their KLN root hormone when necessary. but as its getting warmer here in the Mission district of SF im having to water a couple times a week. seems like too much fertilization going on compared to the manufacturer's "production" amounts. not to mention i seem to be going through the chemical $upplies quickly.

my question is this- if i went to a schedule of fertigation once a week (say on weekend when i have time to mix large batches of solution) and then just did plain old H20 irrigation during the week for moisture- do i need to adjust the pH of the water when i irrigate? or only when i fertigate since that's when the nutrients are being delivered and pH is important?