Very fine crystals at bottom of jars of Black Walnut syrup

I tapped some of my black walnut trees last spring (my first experience tapping any type of tree) and made the most delicious syrup. I still have a few small jars left and noticed that they have a very fine crystal sediment on the bottom. These crystals are not rock hard... they move and flow a bit when the jars are tipped. From what I've read since the sediment moves I think it is niter, not rock sugar. Am I right? Black walnut sap has a lot of pectin so I strained the sap through cheese cloth two times rather than a paper filter. I also used a digital thermometer for the final boil but will get a hydrometer for this year's syrup as I may have over boiled it. I assume the syrup is still good but am not sure what to do with the crystalized sugar on the bottom. Any insight is greatly appreciated! Thank you!

It sounds like niter and should not hurt anything.

I am a professional at screwing up the filtering process, and I can say from my experience, it's niter that you are seeing. Especially since you just used cheese cloth and not the standard paper pre-filter + orlon felt filter. I had a ton of syrup with niter in the bottle, and it settled after a while so I dumped the clear syrup into new bottles and heated it back to 180 in my oven, then gave it a new lid.

You described niter (or sugarsand) to a tee, 2 names for the same thing. You need better filtering. When packing the syrup, use a filter made for maple syrup, I like Orlon best, then use 3,4 or even 5 prefilters. Depending on the quantity you are doing, use cone filters if only batches of a gallon or 2, use flat filters if for much more. Flat filters need a rack, something to lay them in to then let the hot syrup flow thru. In either case as one prefilter gets plugged, lift it and very slowly dump it into the next pre-frilter. Repeat as necessary. In either case, both the pre-filters and the orlon filter can be washed, use hot clean water, no soap. Change the hot water as many times as it takes until the water looks clear after squeezing the filter in the hot water a few times. Just squeeze the filters, never wring them. If you wring a filter you break some fibers and essentially ruin that filter, it will no longer filter properly. Hang the filters to dry.
One thing also that can help is to add a little food grade diatomaceous earth (DE), available from maple dealers or if you just need a little, look into buying it from a local maple dealer. When adding the DE, stir about 1/2 cup in 1 gallon of hot syrup, then pour the mix in the filter. Keeping the syrup hot while it filters helps a lot.