You've probably noticed, but that river bed is going to fill in with darker substrate sooner than later. Do you have any sort of dividing wall in there? The tank looks good so far, a shot of it cleared up would be interested. As for the solenoid, I can't really suggest one. But check out some of the regulator builds in the DIY or even the for sale section and see what they are using.
To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.