I picked up a couple of limewood airstones at a LFS today because I am going to run CO2 mist along with my reactor.

I am going to order some more online but I had a few questions about the airstones before I place an order.

1. The limewood airstones I bought said to replace them every 3 or 4 weeks, is this the lifespan that I should expect from them?

2. I saw the Coralife brand and a Lee's brand, is one brand any better than another?

3. What type of maintenance should be performed on them?

Thanks,
Bill