Water Hardness

[gibbs.david]

I’m struggling to keep the water hardness above 8 and each time I get it there it appears to deplete back to 7. I’m currently dosing 15 ml but somehow isn’t enough to keep it stable. The tank is 145 litres

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[James M]

8 is a good level. I wouldn’t worry as your inhabitants look great

 

[sghera64]

If your dKH is dropping from 8 to 7, then you are likely doing a lot of things right as this often signals that your stony corals are taking up that bicarbonate swiftly. One exception is if you pH is too high and Mg very low. In that case you will see a lot of white crust on things like pumps and heaters.

I would say be happy and keep maintaining things as you are. If having to add bicarbonate/carbonate is too much or too expensive for you then leave it at 7 and coral growth will adjust and slow down, reduce lighting intensity or flow.

 

[AdamNC]

You need to dose daily now or get yourself a dosing pump.

 

[gibbs.david]

Ive increased dosing to 20ml dosing twice a day. Probably need to reprogram to four times at 5ml and monitor

 

[Randy Holmes-Farley Verified Community Expert]

A drop in alkalinity of 1 dKH per day (you don't say how long that drops takes) is perfectly normal.

FWIW, you are not measuring what is normally referred to as water hardness, which is a different thing. Refer to it as alkalinity when communicating to others.

"Hardness" is a total measure of calcium, magnesium, and some minor ions like strontium.