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Re: Sterilizing tank

I'll just paste in the significant stuff.

Eric writes:

<snip>> I talked to the people at
>  my LFS and they kept telling me that only carbonate hardness (KH) mattered,
>  not general hardness (GH). My GH was around 600 ppm, and I mentioned my
>  concern to my LFS. They said don't worry. Later I found out (while reading
>  an article on the Krib web page) GH is what is meant when fish people talk
>  about soft water! I printed up the article and showed it the owner of the
>  LFS and he still said it didn't matter. I said screw him and I fixed the 
>  The fish seemed to be fine.
>   Starting about a week and a half ago a lot of hair algae (I think) has 
>  showing up. I have a feeling it is due to a lack of CO2. I was going to buy
>  an injector early this week.
>   I can't get my pH down! I tried adding Seachem acid buffer and got my pH
>  down to 6. Then in a few days it would go back up to about 7. I fought this
>  for about a week, no luck stabilizing it. I then filtered it through
>  Canadian sphagnum peat. Didn't change it. My tank has been like this since
>  day one.

Both GH and KH matter.  GH is the concentration of +2 valence ions, measured 
as if they were all calcium.  KH is the measure of carbonate hardness, but 
measures all buffering capacity as if it were carbonate.  This is also known 
as alkalinity.  Alkalinity is the water's ability to resist a reduction in 

Usually, when GH is high, so is KH.  Now, why is it so high?  First, check 
the GH and KH of your tap water after it has sat around in a CLEAN glass for 
8-24 hours.  This allows it to stabilize.  If it isn't as high as your tank, 
go to a hardware store and buy a quart of muriatic acid.  This is nasty 
strong, so be careful with it.  When you get home scoop out some gravel from 
the bottom of the tank.  Put it in a glass container, like a measuring cup or 
a drinking glass.  Then set it in the kitchen sink, let the faucet run, but 
not into the container.  This will protect your plumbing from the muriatic 
acid, and also remove some of the fumes out of the air.  Now, CAREFULLY add a 
little acid to the container.  IF it fizzes, there's your problem.  The 
gravel is causing both GH and KH to rise as the limestone, seashells, crushed 
coral or whatever is in it dissolves.  You have to replace it.  If it isn't 
coming from the tap or the gravel, then you have something else in the tank 
that is dissolving.  Figure it out.

Now that you have everything else under control, you are ready to try 
controling your pH.  Acid buffer is alchemy.  It turns a bunch of the 
manufacturer's useless chemicals into gold, while turning your gold into a 
lot of useless chemicals.  If you find that your water is very hard right out 
of the tap, you need to use RO, DI or LOTS of peat.  If it is medium hard you 
can use less peat, or Mardel's TankSoft.  If it is the gravel or decorations, 
you need to eliminate them.  Any other approaches will lead ultimately to 
trouble for your fish.

Check this stuff out and get back to us.

Bob Dixon

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