What Ca based amendments were you top dressing with?
Are you 100% certain the water itself is Calcified?
Have you done any soil pH tests with both your well water
and distilled water?
A few thoughts before receiving the answers to the questions above.
160ppm is fairly low. My water tests between 400-440ppm, personally. My well water is 7.5pH at the lowest and typically around 8.0 on average.
I'm quite confident the issue with my water is it has a form of Calcium Carbonate in it for multiple reasons.
1) Anything in contact with this water sees scaling within a matter of a week. Even letting water evaporate in a glass cup will show rings.
2) The water itself always buffers back to 7.5-8.0pH. I did a test for a few days with a shotglass full of water and pH testing liquid. Liquid was always 8.0pH in color. I would squeeze lime, vinegar, and even pH down into the water until the red color for 4.0pH would show. Within 24 hours, the color would always reverse to 8.0pH.
Both of these factors lead me to believe there is some form of Calcium Carbonate within my water, there is nothing else that I personally know of that can keep a pH buffered this high.
I used to buffer my peat moss with dolomite lime, bringing the pH to around 6.5-7.0 or so. Adding my 8.0 pH water, combined with the salt build up from said water, resulted in my soil pH being the same as my water; 7.5-8.0 pH.
Removing all buffering agents (OSF/Lime) and Calcium inputs (Crab Meal, gypsum) was the only thing that worked for me. The 8.0 pH water combined with the 4.0 pH peat moss kept my pH at a perfect 6.0-6.5 pH. The water also provided me with sufficient Calcium, while mixing Epsom Salts into the soil (and foliar feeding with them) provided me with sufficient Mg. The outdoor plants in this soil provided the best yields and quality I've ever had since living on this well. I did have to start with new soil, buying new peat moss and ensuring it had zero dolomite lime in it.
The key to this is in two things though;
1) You must be absolutely certain that your water isn't just calcified,
but that it buffers pH as well.
2) You
must use peat moss for your substrate. The acidity of the peat is mandatory in balancing the well water.
Again, everything above that I've said assumes that your water is capable of buffering pH.
Since you're on a well, this is likely. Municipal water typically has it added in, so it doesn't have much buffering ability.
Well water, on the other hand, has minerals that have dissolved over time and
will end up in your water source without some sort of filter.
My recent grow is using a peat moss based soil, hardware store didn't have peat moss bales. I went with this soil because it listed zero buffering agents in the list. The assholes must have just not listed them, and perhaps thought the consumer (me) would
assume it had buffering agents in it already. Now my well water is fucking things up again.
The following two products are helping me somewhat, but it requires consistent work and is not as perfect as my last batch of soil was. I will have to make new soil next time, you will too.
Calcium filters and
Liquid soil acidifier
The Fertilome product can be had cheaper at a hardware store, if they sell it. My Ace Hardware has it for $10/bottle instead of $15.
I use it every other watering, only thing that is remotely helping. I pH tested the Fertilome infused water after 24 hours, the pH never buffered back to 8.0 and stayed where I left it.
This is of course a pain in the ass for my 20+ plants. I have to mix buckets fill of this solution, adding small amounts of it at a time until my pH tests show a 6.0-6.5 pH, and then water the Fertilome infused water in manually every other watering. Does the job, but isn't as ideal as if I had just waited another week for peat moss bales. Price I pay for not wanting to make the 2 hour commute again.
The sulfuric acid reacts with the calcium carbonate, breaking the Calcium Carbonate apart into something that won't buffer your soil's pH anymore.
Normally I'd agree with this 100%, as low K will prevent Ca or Mg from even being absorbed. But I'm seeing more deficiencies on OPs plant than just those, so I'm inclined to believe this is a problem with the pH being out of whack as opposed to excess Ca.
If OPs water is truly capable of buffering pH and he is top dressing with something like OSF (which is also a buffer) then I can see how all these deficiencies would be appearing.
This looks more like a pH issue to me, personally.
If you look closely at the 2nd to last picture, you'll see lots of purple petioles as well as a bluish "sheen" on the leaves themselves which points to P being locked out as well.
I was afraid of this. OSF is a pH buffer, so if you already have a pH buffer in your soil (OSF or lime)
and you've top dressed with OSF then you have overlimed your soil. The pH of your soil is certainly out of whack now, unfortunately.
If at all possible, do a couple tests to confirm this.
1) Test the pH of your runoff
2) Take some soil from one of your plants and let it sit in your water for 12-24 hours. Strain the soil from the water, then pH test the water itself.
If the pH tests from both tests show a pH of 7.5 or higher then your pH is too high and is causing all sorts of lockouts like I'm seeing in the pictures. Anything higher than a 7.0 pH is going to cause lockout of some sort.
Sorry I couldn't give better news.
And sorry for the book, replies kept coming in as I was typing this.
tl;dr: Too much buffering agents in the soil, pH lockout is the problem here IMO.
