Downward Curling Leaf Tips

So my girls have been doing EXCELLENT up till this point.

They're in FF Happy Frog soil. I have been giving them the fox farm trio they're whole life span with no other nutes. I give them a feed every other watering and it's down to needing to be fed/watered every 3 to 4 days. I have a mars hydro 1000 light turned up to 100% at about 18" from the middle canopy.

I tried this last feeding not giving them the big bloom because everytime I add all 3 of the nutrients (in order big bloom, grow big, tiger bloom) with stiring thoroughly in between adding the next, the ph would lock out at around 5.4 so I did a test to see if it would do it without the big bloom and it still happened. It's been about a week since last feeding, the ppm was around 540 and they've had 1 ph balanced watering as of yesterday. It looks like the leaves are starting to curle down and slightly burn at the tips all around the plant not just at bud sights. Other than that the leaves are super green and healthy but im wondering if switching the feeding by taking out big bloom may have fucked something up or threw them off some how. Also while I'm talking about this, does anyone know why the ph locks out after adding all the nutrients? I don't know If I need to start adding them separately to water instead of all together? Any input is appreciated.

Yes, leaving a part out of a 3 part will cause problems.

Your plants are fine. They just look over fed. I'd assume the base soil is a bit hot. With the fertilizer making it hotter. They're not too much over fed but they could use less fert.

Tiniest bit over fed. I'd probably go plain water next feed and then 50-80% nutes on future feeds.

For sure thanks for input. Do you guys know what could be causing the ph lockout when im adding the nutrients together? It's in the last part of my initial post.