How do i stop small bits of cabbage from floating past my weight to the surface of sauerkraut brine?
I know of four approaches to this problem:

A better-fitting weight. The wider the weight, the less will sneak up around it. This can work very well for a wide-mouthed vessel. This is what my grandma and great-grandpa used to do—use a barrel, bucket, or wide-mouthed crockery with no narrowing at the mouth, and put a same-sized plate on top with rocks to hold it down. But for smaller batches in something like a mason jar, the narrowing at the mouth prevents a wide weight, even for wide-mouthed jars.
Saline-filled ziploc. This is sort of a corollary to #1 since the ziploc can fit any space. Some people fill a ziploc bag with brine and rest that on top of the ferment. My brother does it this way. The benefit is that the bag can spread out to block any sized opening. I don't care for this approach, though: Either the top of the baggie will protrude above the surface of the fermentation brine, making it a little harder to remove any yeast and mold that develops, or else you'll need to put it so far down in the vessel under the brine that it reduces the amount you can ferment.
Use crossed &quot;carrot planks.&quot; Sometimes I've cut a large carrot lengthwise into something that looks like small orange wooden planks. Then I place those flat on top of the fermenting vegetables, crossing two or three of them. If they're long enough to reach the whole way across the mouth of the vessel—and ideally a little longer so that you have to tuck the ends downward a little around the vegetables— they do a very good job of minimizing floating bits. Downside: I've found when I do this, the ferment is more likely to develop a layer of yeast floating on top (kahm), presumably from the sugar in the carrots. Kahm is benign and easy to remove, but I don't care for the slight yeasty flavor it imparts.
Don't worry about it. My preferred method. Unless the weight is just too narrow for the vessel, after a few days the bits that are going to float will have floated, and the rest will reach a kind of stasis. I monitor ferments daily for the first few days anyway, so it's no hardship to scoop off anything that floats. And I've found that once ferments get past the early stages of fermentation (a week or two), things become less likely to float anyway. The first stages are heavy in CO2 production, which is why you see lots of bubbles initially, and those bubbles lift things to the surface. As early-stage lactic acid bacteria die off and are replace by the later stages, you'll see much less bubbling.