Hi Jerry, are you also using clay pots on those Phals?
I flush the pots as often as once a week and then sometimes every two or even three weeks. I've checked the ph and tds of the reservoir water, too. I never just fill the reservoir, I always fill the sh pot to the top and let it drain at each watering. (That's the part of sh I'm not fond of as it uses alot more water each watering.)
A friend of mine grows some of her Phals in clay pellets only (no sh) but she's in a gh situation. I'm trying that on a few myself but, so far, they're drying out very, very quickly. No gh.
But the humidity is acceptable, ranging from 50-62% and a bit higher on rainy days.
Now I've switched to the MSU fert...sigh...the learning curve with sh is a bit trying, at least for me.
Nice to see you posting here!
Maggie