Tropica soil raising my KH

[meto1986]

Hi all,
After few months of thinking I decided to start using RO water for my planted aquarium. The main reason was my struggle with Rotala macrandra and Wallichii.

I have tropica soil on the top with seachem flourite underneath and then a mix of fine and small gravel at the bottom. Not ideal but I started with only one layer of fine gravel, then decided to use soil so found it is easier to dump it over what I already had + it will reducd the depth of my tank to help with lighting as it was 55cm.

When I added the soil a year ago my DKH dropped to 0.
My tap water is hard with DGH 16 DKH 10, after a running this setup for a year I recenlty moved to RO water and my target values are DGH 6 DKH 3.

NO matter what I do, I cannot get the DKH to go below 5 DKH, I 've done multiple big water changes with RO water. It drops to 5 and then gets up to 7 in couple days. (Tested my RO water and it is close to 0DKH).

My humble explanation is the soil absorbed KH through the first year and now it is releasing it back into the ro water.

Will that change by time? How long I need to wait to get the DKH level I've always dreamed of.

Any quick fix to do?

Many thanks,
Meto

 

[MoFish]

Do you have any rocks in your aquarium? if so which kind?

 

[Bradders]

Hello - I am not a wizard, but does this thread answer your question? Basically, the explanation to why aquasoil can stop working....

Post in thread 'KH, GH and aquasoil'

8 Jun 2023

Hi all,

I am assuming the soil will stop softening the water over time and I will eventually be back to tap water values in the tank??
Why does the soil do this?

The Aquasoil will eventually stop "working", this is because it works <"via ion exchange"> and all the <"protons (H+ ions) in the soil"> will have been exchanged for <"calcium (Ca++) ions from the tank water">. This ion exchange will <"reduce dKH as well">, because the addition of protons ("acid") will <"convert some the dKH (the HCO3- ions) into CO2"> which will outgas.

What would be...

• dw1305

• 

 

[Zeus.]

If its not other hardscape ie rocks, it could be the AS. Using RO water in theory should slowly strip any surplus Ions and Cations from the AS, which may be the source of the kH in the tank.
How many WC it takes I dunno, but keep us posted on what happens.
Plus what rocks you have!

 

[meto1986]

Do you have any rocks in your aquarium? if so which kind?

I don't have any rocks, the gravel I have is Unipac Kivu and Pets at home premium gravel.

 

[meto1986]

Hello - I am not a wizard, but does this thread answer your question? Basically, the explanation to why aquasoil can stop working....

Post in thread 'KH, GH and aquasoil'

8 Jun 2023

Hi all,

I am assuming the soil will stop softening the water over time and I will eventually be back to tap water values in the tank??
Why does the soil do this?

The Aquasoil will eventually stop "working", this is because it works <"via ion exchange"> and all the <"protons (H+ ions) in the soil"> will have been exchanged for <"calcium (Ca++) ions from the tank water">. This ion exchange will <"reduce dKH as well">, because the addition of protons ("acid") will <"convert some the dKH (the HCO3- ions) into CO2"> which will outgas.

What would be...

• dw1305

• 

Thanks for sharing it, it is similar question however in my case the soil is not neutral (depleted) it is changing the chemistry in opposite to what is expected when it is active.

 

[Bradders]

Thanks for sharing it, it is similar question however in my case the soil is not neutral (depleted) it is changing the chemistry in opposite to what is expected when it is active.

So you complete (95%+) water change with RO at 0dKH, which starts at 5dKH and then rises to 7dKH?

 

[meto1986]

I don't have any rocks, the gravel I have is Unipac Kivu and Pets at home premium gravel.

Will keep everyone updated on this, I don't have any rocks, the gravel I have is Unipac Kivu and Pets at home premium gravel.
I use Seachem matrix in the filter which in theory shouldn't affect the KH.

 

[Andy Pierce]

I have the same experience. I have recently reduced alkalinity and notice it creeping up over a week from 15 ppm to 75 ppm. I gave it another water change today and we'll see how that goes. The tank has years old aquasoil but no other alkalinity sources that I know of.