New five gallon planted tank

[StevenF]

And what do you do, defrost it and replenish your 20ml pill bottle and then refreeze? Or once it's defrosted is that it??

I refreeze it.

According to Seachem, the mold is harmless

The moldy fertilizer will still work as a fertilizer. However some molds are known to be toxic to people . Don't know if they are toxic to fish. Regardless I don't want to take the chance.