Usually means you're watering too fast or the soil has compacted and needs to be aerated (large screw driver plunged from the surface to bottom of pot about 2-3 inch spacing). Next time use more perlite.
Transplanting also helps. I go from solo, 1g, 3g, to 5g air pots. Every time I transplant the plant gets fresh soil. This keeps the roots healthy and gives them room to grow.