ALK Precipitation In Mixing Station

[mic209]

I usually mix 15 gallons of saltwater at a time in a brute container in the garage, this lasts me around 3 weeks. I always keep a power head and heater on in the container. For some reason my ALK will drop after a week, but calcium will stay the same. Last week it was at 9.0 DKH today it was at 7.2 DKH on read sea pro test kit. What can I do to prevent this?

 

[downbeach]

Do you see a crust forming on your PH and heater, sides of container? That's where it's going. Your Ca is probably going down a little too, but since there is more of it in reserve in the water, it's not as noticeable. I mix mine and allow it to mix and aerate for two weeks between WC's, so I just make an adjustment using my two part before I do the WC.

 

[Dr. Reef]

heat from the pump and heater and elements will cause the alk to precipitate over time.

 

[bertoni]

Is there any precipitate on the tank walls or a bit on the bottom as sand?

 

[mic209]

There is a whitish brown dusting on the sides and on the pump and heater.

 

[bertoni]

Well, some of the mix might have precipitated as it was added to the saltwater, or it might have converted to very fine sand during storage. Once any precipitate is out of the water column, the alkalinity reading of the kit will drop, because the alkalinity test works by acidifying the water, which would dissolve the precipitate, and artificially raise the alkalinity level.