Flourite Black Sand dumping GH and KH

jonny_ftm

Guru Class Expert
Mar 5, 2009
821
2
16
Hi,

Facing difficulties to lower my GH and KH in my RCS 45L, I made this test:

I filled half of a drink glass with Seachem Flourite Black Sand. Added RO water (KH 0.6) to fill the glass and stir it. After 3 weeks, I tested:
KH 5.4
GH 8

:mad:
Just shocked. Is this how my tank would go if I didn't make weekly 50% WC? Seachem insist that their substrate is inert. I had really big doubts seeing how much calcium carbonate it holds, but trusted them.

I'm very angry as I really targetted a lower KH than my actual 2.4. Also, I hate those swings of making 50% WC with a KH of 0.6 and it always ends in 2.2. I'm not sure my RCS appreciate this, especially the babies.

So, despite its success, I would never recommend it again