Filters, Malachite Green and pH levels...?

[eastofthesun46]

Hi
I have been having issues with my filter lately, mostly due to overenthusiastic snails getting into the motor.When I came home tonight, I noticed that it wasn't blowing any bubbles. I checked and cleaned the filter (but could find no blockages..?), fiddled with the motor for a bit and turned it back on - bubbles, but not very many.
In the mean time, I re-oxygenated about 40% of the water by means of a jug, and that seemed to calm the fish down. I also did a test strip to check ammonia levels, which were fine, and noticed that my pH level has risen from 7.6 to 8.3 since I changed the water yesterday. I did dose it with Interpet Anti White Spot last night, which has about 47mg of Malachite Green Oxalate per 100mls. Was wondering if anyone else has noticed this happening, or if I should try to find another cause?
All of the fish seem pretty unperturbed by it all, luckily.
And any budding engineers got any ideas about the filter? It is less than 6 months old and has been working fine up until the last few days or so. The water flow still seems pretty good, I'm just missing the bubbles!

[Diana]

What brand and model of filter is it?

Test the tap water for pH, GH and KH. Has this changed from the last time you did a water change?

[eastofthesun46]

I tested for everything, and nothing has changed except for the pH level.
It's an interpet PF2 filter. I replaced a couple of parts when I cleaned it for the second time last night, and for the most part it seems to be doing ok. Still, it would be nice if I could rely on it to work... :S