Phragmipedium fertilizer build up -> rinse?

[tropterrarium]

I just have one Phrag. pearcei. Phrags like to sit in water, so I put it in a deep tray, and water with RO & fertilizer (around 300 TDS). Once it dries up in tray (sphagnum still wet), I water again with fertilizer, … Water evaporates, but excess fertilizer does not wash away like in most other pots, because the pot sits in a deep dish.

So I did an experiment, and rinsed the pot with pure RO and stuck a TDS meter in the run-off: 1900. Yep, one thousand nine hundred. Seems a bit much.

First, is this a problem, or do I invent problems?
If that TDS count is too high, how do you keep it in check?
I rinsed my pot several times with pure RO, but given the thick sphagnum, a lot of nutrients are absorbed by it. Took about 5 washes to get it below 800.

Any old Phrag. hands having any insights?