Make sure to put the siphons on very lightly.
Sometimes the smaller seeds are a little more challenging to grow as they sometimes get stuck and it is normal to have to clear them from the siphon with a toothpick.
For the rinsing process, the trick is to use a jug of water and to fill to the top of the first tray all at once. This will create a strong water pressure to be able to push and drain from one tray to the next.
Regarding the mold that some people mention, if it is indeed mold then that would be a result of the germinator not draining properly or there is too much humidity in the tray or even in the home. Normally, some types of seeds produce ultrafine fibrous roots (white fluff) that are easily mistaken for mold, but they’re not. You can see when touching it that it disappears. If in doubt, just rinse before consuming.