I keep wild discus.
In SoCal, the water is extremely hard, so all weekly cleanings are with RO water. I add buffers to keep KH up, but I use very little tap (5% or so).
Last week, we put in a water softener and when I test hardness, it is at 0. However, I understand that water softeners don't really soften water per se, but change the Ca and Mg ions for K or Na (I am using KCl). Since the hardness testers don't test for K, the readings are 0, but this does not mean the water is pure.
So my question is: since the water hardness test kits only test for Ca and Mg, am I OK to assume that high levels of K are OK (yes, I do have a planted tank, but I cannot measure how high the K is, since the water is very hard, I would assume it is quite high), or should I stick to RO which is closer to the real rainwater they see in the wild? What about 50/50?
Anyone have any luck with softened water with Discus? Do you think they will notice the difference?
Next cleaning is tomorrow so thanks in advance.