# Meaning of rising kH



## tiger15 (6 Sep 2018)

I have a dirt substrate Walstad tank. It started out with kH 4 and gradually rose to kH 6 as the plants filled out in two months.  I haven't done any water change or dose anything.  

What is causing the rise in kH?   Does it mean my gH is also rising?   

I only have a kH kit and haven't tested for gH for ages.  My water company reported kH 4 and gH 6  in my tap water.


----------



## Zeus. (6 Sep 2018)

Minerals dissolving out of rocks, wood and substrate will change the kH plus water evaporation too


----------



## dw1305 (6 Sep 2018)

Hi all, 





Zeus. said:


> Minerals dissolving out of rocks, wood and substrate will change the kH, plus water evaporation too


That would be my guess, unless you've been topping up with DI water?
You would expect that dKH would decline over time as carbonate was consumed during microbial nitrification. It is called "old tank syndrome" all thought it tends to be much less of an issue in planted tanks.

cheers Darrel


----------



## rebel (7 Sep 2018)

Have tested your tap water just to be sure.

Only way that kH has increased is for something to be releasing 'it' into the water. Usual culprits are alkaline stones.

In theory, wood, livestock and plants should reduce kH.


----------



## Keith GH (8 Sep 2018)

tiger

It would help if you posted a few photos of your tank plus test your own tap water.   

Keith


----------



## sparkyweasel (8 Sep 2018)

tiger15 said:


> I have a dirt substrate Walstad tank


What was the source of the 'dirt'?


----------



## tiger15 (9 Sep 2018)

It's dark, loamy to clayey dirt I dug out from my garden.  Rock is Dragon stone that looks like brown claystone.  I have no drift wood.   Plants grow well with 4 hour direct sunlight from window.


----------



## Keith GH (9 Sep 2018)

Tiger 

That narrows it down a lot.

Your garden soil see if you can find a garden nursery to do a full soil test for you.

You can dig a little soil out add some tap water and test that over a period of a few weeks and see what results you get.

Have you tested the tap water if so post the results please.

Keith


----------



## tiger15 (9 Sep 2018)

A recent report of  tap water from my water company:

Fe 0.16
Otho P 0.12
Alkalinity 4
Na 8
Cu 0.2
Ca 22
Mn <0.01
pH 7.6
Conduct 395
Nitrate 1.8


----------



## sparkyweasel (9 Sep 2018)

As Keith says, get your soil tested, or get a kit to test it yourself. It may well have some chalk or limestone in it, either naturally or added by a previous owner to improve the soil.


----------

