It's really hard to see from the pictures what's happening, but if your description is correct and the leaves are paling round the edges, then that strongly suggests Potassium is getting locked out.
Magnesium affected leaves yellow from the tips inwards towards the centre of the leaf, then turn necrotic at the tips, they don't yellow round the edges. That you used plenty of Dolomite lime in the potting mix also supports the view that it isn't Mg.
A lot depends on how long they've been in those pots/soil and how much mineral/chemical nutrients you've been feeding them, you've probably got a light salt build up in your soil, that's beginning to lock out Potassium.
I wouldn't flush them though and I wouldn't bother with changing the water ph either, that lime in the soil is more than enough to buffer the ph to an acceptable level, a ph of 7.5 is not enough to cause nutrient lock outs, but high soil salinity is.
I would simply feed them plain tap water with say 10-20% run off for the next couple of waterings and then start a light feeding of a standard 'grow' nutrient, with none of the other additions you're using until they're stabilised.
I've also noticed you have your plant pots in saucers, make sure the plants don't suck up any watering run off, (ie don't let them stand in that run off) because they'll be sucking back those dissolved salts. When you water them, throw away the run off, don't allow them to suck it back into the soil medium.
Expect them to get a little worse before they get better though, as the plain waterings will remove some of the plant nutrients from the soil as well as the dissolved salts.
Magnesium affected leaves yellow from the tips inwards towards the centre of the leaf, then turn necrotic at the tips, they don't yellow round the edges. That you used plenty of Dolomite lime in the potting mix also supports the view that it isn't Mg.
A lot depends on how long they've been in those pots/soil and how much mineral/chemical nutrients you've been feeding them, you've probably got a light salt build up in your soil, that's beginning to lock out Potassium.
I wouldn't flush them though and I wouldn't bother with changing the water ph either, that lime in the soil is more than enough to buffer the ph to an acceptable level, a ph of 7.5 is not enough to cause nutrient lock outs, but high soil salinity is.
I would simply feed them plain tap water with say 10-20% run off for the next couple of waterings and then start a light feeding of a standard 'grow' nutrient, with none of the other additions you're using until they're stabilised.
I've also noticed you have your plant pots in saucers, make sure the plants don't suck up any watering run off, (ie don't let them stand in that run off) because they'll be sucking back those dissolved salts. When you water them, throw away the run off, don't allow them to suck it back into the soil medium.
Expect them to get a little worse before they get better though, as the plain waterings will remove some of the plant nutrients from the soil as well as the dissolved salts.
