Sodium Bisulphate

[sammo2001]

Hi all,

I have just cycled my new 250 litre tank and have done a water change so ammonia, nitrites and nitrates are all zero. Now I am trying to get the pH to sit at 7.0 by using a product by AquaOne called pH Down (basically sodium bisulphate). I am getting very strange results and am hoping somebody can shed some light on the situation.

The water from my tap has a pH of 7.49 and a dKH of 5.0. If I add API Stress Coat the pH goes up to 7.56 and 5dKH. I then had to add quite a lot of pH Down to get my pH down to 7.02 and stay there for more than a few hours but now my dKH has gone up to 9.0.

As I understand it, after the addition of the pH Down both my pH and my dKH should have fallen. Has anybody got a clue as to what is happening?

 

[sammo2001]

Just did a little test and added enough of this pH Down to a small jug of water to bring the pH down to 5.30 and strangely the dKH went way up to 16.
This is not what I expected.

 

[Mumma.of.two]

May I ask why you are trying to alter the pH?

 

[sammo2001]

Oh sorry I forgot to mention that the pH eventually rises to 8.12 once in the tank. Takes a few days though.

 

[sammo2001]

Wow just read a thread online about pH reducers affecting phosphate levels. I just checked mine and the levels are through the roof! Am going to water change a huge amount and stop using pH down. I think I'll just leave the pH at what ever it sits at naturally.

 

[BillD]

Good idea. Using pH down or up, needs to reduce the buffering capacity of the water before it has an effect. Without buffer the water is unstable so you will see swings in the pH. Best to live with the water you have unless you enjoy playing water chemist.