I almost lost it at one point. About a year ago I made some changes to all my phrags that has them just exploding.
1) Potting material is 1/3 medium to small lava rock, 1/3 rockwool cubes, 1/3 medium orchiata bark. Crushed oyster shell or prilled dolomite lime is mixed into the mix if the plant has any kovachii in it's background. Sometimes I forget to add it and then I just sprinkle some on the top and refresh it every few months.
2) Water is R.O. that after fertilizer is added I make sure is adjusted to a ph of 6.5 to 6.6
3) I rotate fertilizers between Jack's 30-10-10 and MSU 13-3-15 RO/Rain Water Fertilizer. I shoot for 100 ppm of nitrogen. I add a liquid Cal/Mag to the Jack's since it doesn't have any. The MSU contains calcium and magnesium so I just go with what it has in it. I also add to the water 2ml of Orca Liquid Mycorrhizae Mycorrhizal Fungi Root Stimulator and Booster.
4) I water at least once a week. When I say water I perform what I have seen described here on the forum as 'fertigation'. I hand water all my plants on a frame that I place over the drain tub for my washing machine and liberally flush the plant with plenty of water. I seldom if ever flush with plain water. Sounds of lost of work I'm sure, however I am retired and I have lots of time to baby my plants.
5) Lighting is with LED lights set to provide roughly 200 ppfd. Lights are on 12 hours per day during my winter here in Minnesota 13 hours in the spring and fall and 14 hours during the summer.
6) All my phrags are grown in my basement where the temps during the winter range from 70 during the day and 64 or so at night. I try to keep the humidity above 40% which can be a challenge in Minnesota during the winter. During the summer the temps never goes above 78 and humditity kind of takes care of itself sticking around 50% without any help from a humdifier.
I think that what has given me the best results is making sure that my water is adjusted to a ph of 6.5 to 6.6 after adding fertilizer Also the potting mixture I'm using now combined with the fertigation method of watering has resulted in plenty of oxygen getting to the roots as well as eliminating salt build up.
I don't know which of the above items had the most or least effect on my current success. But only time will tell if it is the holy grail for me or not. As always it goes without saying, what works for me may not work for others.