Using just 20 mule team borax and forgetting the polyquat is fine. I go on vacation every summer 9n July or August for about 2 weeks (and I live in Florida). I just shock the pool with bleach to about 20 ppm before I go (Borate 50 ppm, CYA 80 ppm) and turn everything off. When I come back I have never had a green pool. It might be slightly cloudy but no visible green. I turn on everythng, shock it again with bleach to 20 ppm, and by the next day am good to go. This has been my routine ever since I started using borate over 6 years ago.

You can probably cut way back on the HEDP if not stopping it all together. They say to add the maintenance dose weekly but often it is only necessary montly to prevent stain reoccurance. I would cut back to every two weeks and see of the setains stay away. IF they do after a few months then cut back to monthly.

I would have to say that it's the salt and not the SWCG. I have seen many pools that have never had staining issues with a SWCG. They have used water softener salt pellets or solar salt. Both are actually fine for use in a salt pool. The pellets are very slow to dissovle and can take over a day. The solar salt usually is gone in a few hours. Brushing helps any salt dissolve faster. I have seen several occurances of where pool salt was dumped in and not brushed and it left a stain where it sat. I have never seen that with solar salt.

Citric acid is not the best additive for pool water even though it can be used like ascorbic acid to remove stains. It has some undesirable interactions. I had some info on this but 'get my hands on it at the moment.

The only thing I would ADD to your routine is more brushing!

The phosphate remover is a totally unneeded expense (and will get much more expensive soon if it hasn't already as China continues to raise the price on Lanthanum salts.) Don't waste any more money on it. You would be better served making sure the borate is 50 ppm before closing.