Kh Rising?

[DaveW]

Over the last 3 to 4 weeks my Kh has been rising, from 6 to 7.5. The tap water is 6 and the tank has been since I've had a Kh test kit (3 to 4 months). The only thing I've change is my bogwood, could this be the reason? Should I be concerned? The rest of my stats are:

Ph 7
Gh 9
No3 10
Po4 1

Any help would be appreciated.

 

[George Farmer]

Do you have a gravel-based substrate? I had a similar issue when I had fine gravel.

Bogwood shouldn't raise KH, if anything it may lower it.

 

[DaveW]

I've got plain sand, which has been in the tank from day one.

This may be a silly question, but do any plants change the water chemistry?

 

[George Farmer]

Some plants extract bi-carbonates as a source for carbon i.e. Vallis so this can lower KH. It doesn't explain raising KH though.

I just wonder if your sand has any CaCO3 leeching into the water.

 

[DaveW]

Sorry, what is "CaCO3"?

 

[DaveW]

Googled...... Calcium Carbonate.
As far as I know, the sand is inert.

 

[Themuleous]

Hi Dave,

The other possability is that when you top up the tank with water, I.e. when lots has evaporated, you increase the KH at the same time.

When the water evaporates it doesnt generally take anything with it, so the water left in the tank gets more concentrated. Then when you add more tap water to top the tank up you add more carb/bicarb, incresing the overall amount in the tank.

If your GH is doing the same thing it could well be this. There isn't much you can do to stop this, unless you have an RO unit? In which case add pure RO water when topping up the tank, this'll dilute it back down. If you dont you could try mineral water? Not really sure what else to advise really sorry I guess a 50% water change every now and then would help stop this too.

Hope this is helpful, probably not though!

Sam

 

[DaveW]

I understand what your saying Themuleous, but I do a 40 to 50% water change each week. I think I'll just keep an eye on it for a while.
Cheers anyway!

 

[zig]

Its more than likely the sand.

 

[DaveW]

I'm thinking of changing to dark'ish brown gravel in a while, so I'll keep doing the water changes and keep an eye on it.