Sand bed binding????

[Jacoda]

Is it becoming solid all the way thru, or just the surface?

<font size="2" face="Verdana, Helvetica, sans-serif">Just in areas around the corners of my tank where there is good flow of water.

Are you using a fully saturated solution of kalk? That is 2 tsp/gal. Are you adding vinegar to the kalk solution?

<font size="2" face="Verdana, Helvetica, sans-serif">Ya! I guess I should cut back on Kalk and see.
And yes! I did use vinegar for about a month but stopped after finding my alk was dropping too low.