Currently the water in my aquarium is having a higher pH than I want. What I wonder is if the Cirax filter (and in general biological ceramic filters) affects the pH value (by increasing it, or if it is neutral towards the pH of the water?

I wonder this as I was thinking of adding a second one to my aquarium, but I am afraid of it increasing the pH even more.

1 Answer 1


I don't think that it would affect pH in any way (and definitely would not raise it), but I can't find any source to back this up.

But about 2-3 months ago I added Cirax to my 180 litre tank (47 gallon, Juwel Vision with the stock Juwel filter). I regularly test my pH and did not measure any difference.

About 2 weeks ago I also added one of those blue Juwel sponges, and again I did not measure any differences.

If you're looking to lower the pH then there are a few other possibilities though.

But the biggest changes are probably achieved by adding CO2. JBL has a few CO2 systems with a pH controller. You could configure your desired pH value, and it will automatically add CO2 until that level is reached. But these systems are rather expensive.

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