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.