I have a Rena superclean 40 internal filter. It has a sponge at the bottom and an "API Crystal" cartridge in the middle.
I presume when people talk about filter media this means the sponge.
What does the API Crystal actually do? And do I really need to change this every 3 weeks as per instructions?? Do I even need it at all?
thanks..
I presume when people talk about filter media this means the sponge.
What does the API Crystal actually do? And do I really need to change this every 3 weeks as per instructions?? Do I even need it at all?
thanks..