There is big spacing between the body and the spikes...I've attached two pictures of them... (sorry if it's hard to see!) does that mean they are full of water? Is this bad? Help! I'm worried about my babiess :(
It means that it has got a lot of water and is growing. There is a lot of light green colour, which indicates that the amount of water/nutrients (especially nitrogen in my experience) has been a bit high relative to other factors (light intensity) and has grown a little faster than it should. It does not look critical and will probably become darker green next year. The pot seems big. It depends on the size of the root ball, which is invisible here of course, I am judging from my previous experiences with Mammillaria. What kind of soil is it? It looks quite rich.
It's a soil mixture I bought that was specifically for cacti and succulents. Should I change them into a small pot size? I fear that if I repot them now it won't go well this winter...
At the bottom of my Bristle Brush, the spikes are brown. While from the middle to the top they're white. Does this mean it's dying?
I would wait until spring before repotting. The pot does not need to be more than 1–2 inches bigger than the root ball. Most commercial cactus/succulent mixes are unsuitable for cacti and succulents. A more or less global problem, and cactus forums are full of recipes for better soil mixes. About the brown spines: It is probably brown substances from the soil mix that has dissolved in water, moved upwards and stained the spines. Several cactus species have spines that change colour as they get older, but rarely to brown.
