Looks good. I like the stacks you've made, and I like the substrate. Couple of thoughts. Personally, and since you want feedback, I would take out two rocks. The little round one near the very top of the stack on the left. It doesn't match the rocks in the stack and it kind of stands out. It also makes the stack look precarious, like it's going to fall, whether it is or not. And I'd remove the big round rock in the front on the right. It doesn't add anything and I think it would look better without it. Being able to see the pretty sand and the stack behind it would be nice, I think. Also, consider a black background. I use black backgrounds in all my tanks and it really makes for a classy-looking tank. I helps hide the equipment and it makes the colors of the fish really pop out. There should be black on the back side of your blue backing, just try it out and see what you think.
Your tank looks great, especially for a limited budget. Very calm and peaceful.