KH In tank wont rise????

[axl]

I have added 5 teaspoons of bi carb soda to my 450ltr planted discus tank and the KH wont rise at all, is it the testkit or is it somthing else causing it not to rise.

[ILLUSN]

try adding some crushed coral to your filter, the slow leach will bring the Kh up, the bicarb wil proably take a few hours to register on a test kit, and even then depending on the size and acidity of your tank might be consumed.

[axl]

Can someone help understand my KH test kit, i fill the beaker to 5ml and then it says to add drop by drop until the water changes colour from blue via green to yellow. each drop = 1 dkh,
the problem is when i add the first drop it goes a light blue colour and then i add a 2nd drop it goes to a darker blue but dosent go via green to yellow, i dont understand it can someone explain how it works.
Does it mean that i havent got any hardness in my tank??? Cheers Axl

[DIY]

What brand of test kit is that axl? sounds like it might be AP

Anyway you need to keep adding drops until it changes from the blue colour, it might go a darker blue with each drop but it should eventually change colour to the green/orange/yellow. Keep count of how many drops it takes and that is your KH in degrees.

If you get to 30+ drops and no colour change, you either have a crazy KH level in your tank or the test kit is no good

[axl]

the brand is sera i will give it a go now and see how it goes

[axl]

It has just turned from dark blue to yellow and it took 12 drops there is no way my water has got 12Kh or 214ppm of Kh, my ph is at 7.0 so thats mean 36ppm of co2, i havent even got any pearling happening. I have hardly got 1kh in my tap water

[axl]

Thats is def right which suprised me, i just checked my tap water and it went straight to yellow /orange straight away. Is a ph of 7.0 ok for discus.

[DIY]

pH 7.0 is fine, a stable pH is more important than actual pH level.

[axl]

yeah ya right there, the tank is on a ph controller and im running an airstone 24/7 and the ph is stable at 7.0 at the moment.

[DIY]

Have you calibrated the pH probe recently?

[axl]

not for a while i havent, maybe i should do it

[axl]

just checked it with my ph pen and it says 7.0 so its pretty right at the moment

[DIY]

yeah thay can drift a lot over time, be worthwhile doing it :thumb

[DIY]

Oops posted same time, might be silly question but have you calibrated the pH pen recently to be sure?