Tap water quality in Zurich - good enough?

[murph7]

Based on this discussion

Do you need CalMag supplementation with MSU?

I am wondering whether my local tap water is good enough for my orchids. My phals are reddish so it could be for too much light or for some Mg deficiency.

For a complete analysis - Zurich's Drinking Water

Calcium mg/L 53.3
Magnesium mg/L 7.5
Total hardness °fH 16.4
(10° French hardness = 5.6° German hardness = 1 mmol/L hardness)

As a fertilizer I am using the

Orchid Focus Grow
Click the link for more details.

2.2 : 1.3 : 2.1 (Grow)
Calcium oxide (CaO) (Ca) 2.5 (1.8)
Also contains: magnesium, sulphur, nickel, humic acid and fulvic acid.

Any thoughts?

[Orchid Whisperer]

Your water and fertilizer are providing calcium, so I think your plants likely are getting enough.

There is no Magnesium in the fertilizer, and not much in the water. I would supplement, adding Epsom salts, maybe 1 or 2 cc per 4 liters of water, applied when you are not providing your regular fertilizer.

Red in some of your Phals could indicate a lot of things. It could be Mg deficiency, but unless they are getting cold too, I would think it is more likely that they are getting light that is optimal, or a little higher, and would not worry about it too much.

[murph7]

Thanks a lot, I will try to do some changes on my fertilizer regime.