In the past, everybody thought high GH & KH are not good for many delicate plants, thus we all s'd maintain low KH & GH.
Then we understood that the real problem is with KH mainly.
What is the problem with high KH (if there's one)?
Why do you (TOM) mention here from time to time that high GH is even betterr for plants?
Thanks.

One, the GH is basically 2 plant nutrients, Ca and Mg.
KH is not.

KH, or alkalinity determines pH. We artificially lower pH with CO2 gas, tannins etc, so pH in and of it's self is not critical, nor the real player here.

KH is.

This can and does influence uptake of various nutrients, some plant's enzymes are optimized at lower pH's(think KH though!!).

It's not just CO2 uptake that will help these plants, you have to make sure it's the KH.

Most plants are fine at high KH's, their enzymes are okay with the higher alk levels transporting nutrients in/out etc.

All plants are fine at low KH's on the other hand.
Thus in aquatic systems, KH, rather than pH is the real player in uptake preferences.

Note: traces in general are more available at lower KH's, while macro nutrients are more available at moderate to hard water(KH here, not GH)

GH is what folks remove when they soft their water with salt, the KH is very high, but very low GH.

Regards,
Tom Barr



Regards,
Tom Barr

So, how high is too high for KH? Here in SD, it appears I have a KH of 7 in my aquarium. I didn't care about it since I'm using a drop checker to measure my CO2.

Thanks,