Changing dKH

[Simon_M]

I have dKH at about 7.9 - just done an ICP to confirm my Hanna Reading.

I'm aiming for dKH in the range 7.5 to 8.5. The Red Sea Recipes have either 12 dKH or 8KH and for a long time I've switched to a salt that is doesn't have an elevated dKH.

I have just started to become aware of pH. I originally tested when setting up but then never tested it again assuming it didn't matter (or wasn't easily changed).

The value of pH in a quarantine tank is 8.3 but in my DT it is closer to 8.0. I probably need to remeasure it when lights are about to come on and as they go off that corresponds to start of activity and end of an evening in my Sitting Room where DT is located e.g., CO2 affecting the pH.

What is the value in changing the dKH e.g. elevating it to 9, in controlling/buffering properties vs pH?

Simon

 

[Salty_Northerner]

Along for the ride and be interesting to see what others say.

 

[Randy Holmes-Farley Verified Community Expert]

In terms of pH, the difference between 8 dKH and 9 dKH is 0.05 pH units, not counting any effects that may arise (up or down) from supplementing to maintain those levels.

 

[Simon_M]

Thanks Randy.

0.05 pH is a very small amount! I suppose dKH 8 to 9 is a linear increase but pH is 10x (logarithmic) to change by 1 pH.

If it is only 0.05 pH, why would you want to aim for a higher dKH e.g. dKH of 12 is hard to maintain, mixing water is potentially less stable when stored and precipitation on equipment more likely? What benefits would dKH 9 deliver?

I will stick with the range 7.5 to 8.5.

Simon

 

[Randy Holmes-Farley Verified Community Expert]

People most often use higher alk to drive faster hard coral growth directly, not because of the pH effect it has.

That said, going from 7 to 11 dKH is a more significant 0.2 pH units effect at equivalent CO2.