Low kH Salt Mixes

[lwhillman]

kH levels "out of the bucket" on salt mixes seem to vary a lot from brand to brand. My corals appear to suffer at lower (< 8.5) kH levels.

Am I wrong about corals suffering a low kH levels? And should I choose my salt based on kH levels?

[downbeach]

I ran a predominantly SPS mixed reef for many years with lower dKH ~7.5, so I'd look elsewhere. What are your other numbers, i.e. Ca, Mg and SG? What are you using to measure them with? What about your PO4 and NO3? pH?

[tmz]

The kh of natural seawater is around 7; many run tanks very well in the 7 to 8dkh range.

More alk provides more carbonate/ bicarbonate which can increase growth rates. I prefer to keep the alk in my system around 9dkh.

Constancy in alk is key at a level that suits your specific approach; so, if you want 7, 8 ,9 or...etc just be sure to keep it steady and don't bounce it around too much. Corals take up bicarabonate and covert it to carbonate for use in forming calcium carbonate skeletal mass;swings particulary rapid downward swings at the lower end of the recommended range( 7 to 11 dkh) upset the calcification process ;often the corals don't adjust fast enough to cope with shifts in alk.