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Re: Waterexchange - only if animals in the tank?



Klaus wrote:

> there ist no doubt of frequently exchange the tankwater if animals (fish
> a.s.o.)are in. Is this necessary too in case of an *only* planted tank (no
> animals inside)? For my understanding, in an only planted tank is no

I think there are some good reasons to do water changes in a plant-only tank.

First, when adding fertilizers and trace mixes, it's common to just determine 
the dosage based on one key element (for instance, most trace mixes, you adjust
dosage based on Iron level).  That could lead to excesses of other elements,
and regular water changes will take care of that.

Also, evaporation leaves the dissolved contents behind, concentrating the water
in the tank.   To constantly just top off the tank will result in ever-increasing
hardness.

Another issue is that the nitrification process could slowly consume the
buffering, resulting in a pH crash.   With the low level of nitrification
in a fishless tank, I'm not sure how much of a factor this would be.  A
very organic substrate would probably increase the nitrification, and 
therefore result in a more quickly dropping KH.

Another, unproven but often speculated effect of no water changes would
be alleopathic chemicals produced by plants, which hinder the growth of
other plants.

--
Chuck Gadd
Director of Software Development, Cyber FX Communications
e-mail:cgadd at cfxc_com  http://www.cfxc.com