Creapy Crawlies

Hi Peter

I recently decided to change my UV light in my Bioforce filter ready for the spring and noticed on the top of the sponge filters where several what I would describe as insects similar in appearance and size to woodlice crawling around apparently feeding on goodness knows what.

I regularly clean my sponge filters and have never noticed these insects before although I may have left it a bit longer than usual this time. I have always had smaller creatures approx 3mm long clinging to the UV casing.

Is this normal or should I be concerned,

Many thanks,

Colin