Both work. A drench is more forgiving; a foliar spray at half that strength acts faster but do it in the evening so you do not scorch leaves in the sun.
Yellow between green veins starting on old leaves and moving up is classic magnesium, and in a container of bagged mix six weeks in with daily watering it is completely expected: the nutrients that came in the bag are exhausted at around six weeks and magnesium leaches quickly. Epsom salts at about a tablespoon per five litres of water, applied as a drench, will show improvement in a week. But treat the underlying cause too, which is that you have not fed a heavy feeder in a 40 litre pot for a month and a half. A balanced liquid feed weekly from now on.
It went to 38C in the middle about four hours after I posted this, so your warning arrived exactly in time. Broke it into three ridges and it settled to 33.
Usually to somewhere around 3.4 to 3.6 over a few weeks. Strips are only worth about half a pH unit of accuracy though, so if you plan to bottle for shelf stability rather than fridge storage, a cheap meter is the one piece of kit worth owning.
Not stalled, finished the noisy part. The visible bubbling is mostly the early heterofermentative stage burning through easy sugars, and jalapenos do not have many. Once the pH drops under about 4.2 the population shifts and gas production falls off a cliff while acidification continues quietly. Leave it two more weeks and taste it, it will get rounder and less raw. Adding sugar to restart bubbling gives you a fizzy sauce, not a better one.
Put it somewhere with bright indirect light rather than a dim corner to recover. Recovery is expensive and the plant needs to pay for it somehow.
Once damping off has appeared in a tray I bin the compost rather than reuse it, and wash the tray. It persists, and starting again in clean sterile mix is cheaper than losing a third sowing.
One safety line I hold to regardless of what a photo looks like: if there is fuzz, if there is colour, or if it smells of wet basement rather than sour, the whole jar goes out. Kraut is cheap and I am not clever enough to identify mould species at a kitchen counter.
Depends heavily on soil and weather, but the principle is right. In mild overcast conditions a bed rarely needs daily water once plants are in.
New leaves unfurling with brown tips is the detail that makes this a root or salt issue rather than an old-damage issue. Damage from a past mistake stays on old leaves; new leaves report on current conditions.
Split kefir is still perfectly good, by the way. Shake it, or strain the whey off and use it as a starter for the next batch of vegetables.
They roughly double every few weeks when happy. Everyone ends up either giving them away or drinking a lot more kefir than they planned.
Group the pots together rather than spacing them out. They shade each other's sides and the microclimate in the middle of a cluster is noticeably cooler and more humid.
Buy the weights and skip both if you like: fill the jar higher so the brine reaches the shoulder, and screw the lid on fingertip tight so it self-burps. I have never had a jar explode at that tightness in a 19C kitchen.