Is white silica sand ok to use in a coldwater fish tank?
None of the fish will care, but your Goldfish’s activities reveal why they’re best kept in a tank with large substrate– they will put just about anything in their mouths. If they happen to do this near the filter, and they spit sand into the intake, you could have some impeller issues, so I’d recommend putting some fine mesh, a prefilter, or even a bit of pantyhose over the intake. The cloudiness will clear within a few hours as the particles settle or are picked up by the filter. Silica sand really isn’t sharp enough to harm anything, and really, most sands are silica based. Also, silica sand will NOT contribute to algae growth in any way. Silicon dioxide is entirely insoluble and therefore unusable by algae.
