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[APD] Re: Changing GH

Date: Wed, 10 Sep 2003 18:32:31 -0700 (PDT)
From: "Missy O." <or_ask_oskar at yahoo_com>
Subject: [APD] Re: Changing GH To: Aquatic-Plants at actwin_com

<<Unless you have plants that eat gobs of the Mg/Ca,
the GH should not drop with time. Just add the right
proportion to change water and it should be quite

If you don't mind my askin', which plants use up
Mg/Ca? My gH has crept up from 8 (tapwater level) to
14 degrees during past 7 months.

I guess I was thinking of plants like Val that can derive some of their CO2 from carbonates (bicarbonate?). They cause the remaining Ca or Mg to precipitate out of solution as the insoluble oxide or hydroxide. "Used up" wasn't the correct term.

I'm new to this all, I just started my first tank in March, so I don't know how normal it is. I do leave the lid open to keep the tank from going over 80F, so there's a lot of evaporation and I top it off. Although I'm wondering if some of it is due to Flourish Tabs in the substrate leaching stuff into the water as well...

Evaporated water should always be replaced with RO, DI or distilled, if you want the tank to be stable at the level of your tap water. Increasing the percent and frequency of water changes will cause your hardness to reach a lower equilibrium, but it will still be higher than your tap water due to evaporation.

Another common reason for rising GH is that many gravels contain bits of limestone or shell that slowly dissolve. On the Left Coast, Lapis Lustre is a famous one for doing that. Without it, plants would be tough to grow in the waters delivered to the SF bay area from the Sierras (at 50 ppm tds and GH near 0).


Wright Huntley -- 760 872-3995 -- Rt. 001 Box K36, Bishop CA 93514

"nulla lege sine poena"

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