Saltwater storage tank dropping alk

[ryboy707]

So I have a 20g norwesco tank that I use to store saltwater in and I bumped the alk up to 8.5dkh and two days later I tested the water again and it’s at 6.9dkh. I’m not sure what’s happening since there’s nothing to take up the alk and calcium. I’m using Fritz pro reef salt. Anybody have any ideas??

 

[NitrateKillah]

Alk drops daily. You should only add it when when you are ready to replenish your tank.

 

[r20crazy]

add an air stone... and a pump if dont have one constantly on... or keep lid off/vented

 

[ryboy707]

add an air stone... and a pump if dont have one constantly on... or keep lid off/vented

Ok, I’ll give this a shot, thanks

 

[ryboy707]

add an air stone... and a pump if dont have one constantly on... or keep lid off/vented

How do people do auto water changes then if your fresh saltwater alkalinity keeps dropping?? There’s got to be a way to keep it stable

 

[ryboy707]

Oops, last post was supposed to reply to the other post about alk dropping daily

 

[Randy Holmes-Farley Verified Community Expert]

How do people do auto water changes then if your fresh saltwater alkalinity keeps dropping?? There’s got to be a way to keep it stable

Water changes have a pretty small effect on alk when done slowly. Change 1% daily, then tank at 7 dKH and water at 11 dKH boosts alk by 0.04 dKH per day. If that new salt water dropped to 9 dKH, it is boosting alk by 0.02 dKH per day. That 0.02 dKH per day difference seems very small to me.

 

[Randy Holmes-Farley Verified Community Expert]

So I have a 20g norwesco tank that I use to store saltwater in and I bumped the alk up to 8.5dkh and two days later I tested the water again and it’s at 6.9dkh. I’m not sure what’s happening since there’s nothing to take up the alk and calcium. I’m using Fritz pro reef salt. Anybody have any ideas??

Three possibilities:

1. Faulty testing.
2. Solid calcium carbonate that precipitated on mixing still suspended as fine particles in the water and showing on an alk test, then it settled out and was no longer detected.
3. Later precipitation of calcium carbonate, reducing alk.

All of these happen.