That is a very nice compliment. Thank you and good luck with your experimentation. I forgot to mention that I have round filters that screw into my lenses. One is a four stop, and the other is a 6 stop. Together they make 10. I also bought a square 10 stop filter that attaches to your lenses via an adapter and then you can slip the filter into the filter holder. The screw in filters were the cheaper way to go;but they are not as versatile because they are one size. Some people by round filters that are bigger than their lenses and use step down adapters so that the round filters will work on a variety of different diameters. If you need any help with things or have questions, feel free to ask.
Erich

You have already gotten a ton of good information from Bob and others. I do a lot of long exposure shots at the beach. Generally, I find that the sunrise colors (the beach looks east on the east coast, so sunrise has the sun over the water) are best just before the sun comes up. It is pretty dark at that time of day; but I still use a 10 stop filter very often. With low ISO and f11 or f16 I'll sometimes have exposure times that are several minutes long. The result is that the waves in the surf become completely flat and can give some stunning effects. ( I'll post some here if you want me to; but I don't want to hijack your thread).

You are photographing a stream here and I think that it is nice to have some blur in the water to show movement. But you did not use such a long exposure time as to give that cotton candy effect. Some like that look and others like having some texture in the water. You just have to work out which is your preference. This scene has a lot of light in in and the leaves of the trees are very bright. I think with that kind of look a bit of texture in the water (like you did here) yields the best results. If it is much darker, then a longer exposure can be effective and give a very moody and atmospheric look to the image. Good luck with your further experiments. I think long exposure photography is really fun.
Erich

Just yesterday I saw a YouTube video from a guy that takes mostly sunrise and sunset landscape pictures. He was talking about long exposures and just happens he was talking about the trouble he had with focus. He insisted you have to get out there early find your composition, make sure where the sunset will be, set your shot up with a tripod and get your focus set. You can either use an external camera trigger or use the cameras timer. You need a tripod. If you are going to have the tripod in the water make sure you have the narrowest legs extended. Don't have the water over half of that leg portion of the tripod even in calmer water. The water could shake the camera and he was trying to have as little as possible shake. The best time last only 5 min at sundown. If I had a place I wanted to go I would test my exposure time close to home at about the same time around sundown. You will probably only have time for three or four long exposure shots. You probably won't want your darkest filter. The darker the filter the longer the time obviously. At night he mentioned using f/16 to get as much as possible in focus.