I just checked to see if your phone number was in your registration, but it wasn't. So, I'll go at it here.
I've seen aqua or turquoise backwash sediment from a filter a number of times. In every case I've seen it, there was one key factor: dissolved copper. I hadn't really connected this thread with your heater thread, except in a vague way, till just now.
What's likely happening is that your low pH water had dissolved massive amounts of copper into your water, from your heater and possibly also from your Nature2 units. Now, as your pH comes up, your copper is coming out, possibly as calcium carbonate, since your calcium is so high. This is the best possible outcome.
It COULD come out as copper oxide, and turn your liner BLACK!
Given this apparent monster copper level, let's modify what you are doing somewhat:
#1 - Until the copper is gone, never, NEVER add more than 1/2 gallon of bleach at a time; do NOT let your chlorine get above 2 ppm!
#2 - Find (probably at a pool store) a couple of quarts of polyquat (see www.poolsolutions.com/gd/polyquat ) and start using it, 2x per week.
#3 - Continue adding borax, but no more than 1/2 box at a time.
#4 - Continue to run your filter and pump 24/7.
You've kinda 'gone off the reservation' a couple of time; let me encourage you to stick to the plan, if you want to have any hope of saving your liner. Your pool's pH must have been very, very low for this to happen.
And, yes, extremely low pH plus extremely high copper would give you very clear water. But it's also destroyed your heater, and is likely to destroy your liner.
Your pool is sorta like a guy I knew who went for a checkup, only to find that he had advanced cancer. He was all "but, Dr, I feel fine!", to which the doctor essentially replied, "Maybe, but you are dying", and proceeded to make him really, really sick by treating him with chemo.
Your pool "looked fine", but it was being destroyed rapidly. It may still be destroyed. Extremely low pH, like you must have had, is about the worst thing you can do to a pool. Doesn't usually hurt people, but it 'kills' pools. What's we've done since simply has revealed the serious problem that was there before. The damage is apparent now, but was actually done days or weeks ago. Sorry to deliver such discouraging info, but there's no way to fix things without facing the reality. There's a small chance you can get the pool usable by this weekend, but I wouldn't bet on it.
Draining and refilling might be faster. But I'm just not sure how your liner will do -- a drain and refill stresses a liner, and yours might not survive. I wish I had some magic bullets for you, but I don't.
Best wishes,
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