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15.15. Sterilizing Plants

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Author : David Bogert

Published :

Time To Read :
2 minutes
Difficulty : Level 6

Excerpt :

Alum turns out to be the best way to remove pest snails form aquarium plants.

There are a whole host of “dips” and “soaks” for plants which supposedly “sterilize” the plants or kills all pathogens, algae, snails and worms on the plants. The YouTube channel “Girl Talks Fish” (superb channel, I highly recommend it!) tested a whole bunch of dips and soaks on snails (and ONLY snails). To make a long story short: only a “soak” of one tablespoon of alum per gallon (3.79 liter) for two days did kill all the snails and all the snail eggs without killing the plants.

Salt, bleach, potassium permanganate and copper did not kill all the snails and all the snail eggs despite multiple length of times and multiple concentrations. Very strong hydrogen peroxide dip (25% solution of 3% hydrogen peroxide) for a day seemed to kill snails and snail eggs but also seemed to affect the plants. Alum (potassium alum, KAl(SO₄)₂) turned out to be the best dip.

Geophagus svenii
Geophagus svenii

Note the alum probably did not kill any bacteria or algae but probably killed all the planaria worms and the like in the plants. This is just based on the biochemistry of the two classes of living creatures. Alum is a coagulant which will stop the respiration process in animals. I.e. no oxygen can cross the gill membrane and the organisms suffocate. So any animal will be killed. Plants probably will not be killed as they do not “breathe”.

Note that algae are simply a type of plant. So thinking that one can kill algae without killing plants is just ,…. well… let’s just say not too well thought out. This alum dip does NOT kill algae. And anything which might preferentially kill algae will only reduce the algae “load”, not kill all the algae cells. One cannot “sterilize” out something like algae or bacteria completely as there will always be some algae or bacteria cells which survive.

And this alum is the same stuff used to make pickles that human eat. So it is very safe.