KH droping daily 2dhk without any coral

[tanvirfaeque]

My tank 1 year old 75 gallon trying to have coral soon but my KH very low , started dosing reef carbonate from seachem 75 ml everyday for last 5 days but still my KH is 4dhk. Don't know what consume my KH that fast . I Use tap water which have KH and PH around 9 DHK but every time i add water to my tank and mesure PH stays same but KH deplet within 24 hrs . Need Advice thanks

Nitrate 20
Phosphate 0
Nitrite 0
Calcium 410
Mg 1350

Have 6 fish clown ,dottyback and 4 damsels
Sand argonite 2 inch
40 lb rock

 

[Tahoe61]

What testing method are you using? Is Corailline algae growing?

 

[tanvirfaeque]

Api test kit , not sure I'm kind of new for saltwater tank I attached picture . Thanks

 

[Randy Holmes-Farley]

There seem to be multiple copies of this thread around. Best to limit discussion to one of them.