Filter material - fire clay

[Lucho]

Hi, I´m using granular fire clay as aquarium substrate (under the gravel) and as biofilter material in my WD, it seems to work ok since it just took 10 days to cycle (light bioload).
The problem is my pH and DH, both are too high and I can´t point the culprit besides the clay , does somebody know if this substrate might be leaching?

Current aquarium water params: pH 7.6, DH 12 KH 6.
Water added at WC: mixed RO + filtered tap water, pH 7.0 DH 5, KH 8

any idea?

 

[Volenti]

It's possible, put a sample in a small glass of new tested water and see if it changes the ph there.

 

[Lucho]

It's possible, put a sample in a small glass of new tested water and see if it changes the ph there.

already done that, no measurable difference from mixed RO water with my test kit, I´m going to scale up the experiment... thanks for the idea anyway

 

[Nic]

are you refering too the fire clay that would get mixed with a refractory cement to be used in a fireplace????

 

[Lucho]

are you refering too the fire clay that would get mixed with a refractory cement to be used in a fireplace????

nope, granular aquarium fire clay, it´s an aquarium substrate that comes from Germany I think, my LFS sells it. I´ll check the exact brand next time there.