Those are some BEAUTIFUL Rainbows you have there!!!!
I really, really, really miss my Rainbows!!! I setup my 55g as a planted rainbow tank when I first started doing planted tanks, and I got some awesome fish at a shop in Austin. I had them for a while, then something different came into the Fish Shop I was working at, and I traded the Rainbows out, for what I can't remember! MAN I KICK MYSELF IN THE ARSE FOR THAT!!!! The store I got the rainbows at is now gone, and I don't know if I will ever find the quality of fish I had!!! Anyway sorry about the rant!
I can't wait to see the 40B come together!!! If you are still planning on using the Coal slag "sand" be sure to rinse it VERY GOOD!!!! I have it in my 55g now, and I like it, but it was pretty dirty and OILY too! I rinsed mine in a old 5g bucket making sure to keep the water output MOVING! If not the water pressure and the sand will wear a hole in the bottom of the bucket! I put about 4-6" of sand in the bucket and using a adjustable nozzle on the jet setting and washed the crap out of it! Usually about 8+ times of filling t he bucket all the way up, then dumping as much water as I could, over and over, till there would be just a bit of oil film on the surface of the water. I could never get all of the "Oil" to go away. Then when I filled the tank I put some good carbon and fine filter pads in my Fluval 205s and ran them for a few hours, then cleaned the filters out and added more carbon and normal filter floss and that was it!
I know it sounds like a lot of work, but just go slow and steady, and it won't take too long! The "oil" never hurt any of my fish or inverts after adding them to the tank with the Black Beauty blasting grit! I also run a surface skimmer on one of my 205s, and after doing my first water change and filter cleaning about a week after adding the Black Beauty sand cap, I haven't seen ANY oil residue at all! Others that have used it haven't had any reports of the oil doing any harm either, or at least none that I have read about!
Anyway SORRY about the long post, but I just wanted to let Ya know how I went about using the Black Beauty Blasting Grit! I know it is some work, but my time is worth the $40-$60 I saved by not buying the black sand at Petsmart!
Hope this helps ya some, and feel free to holler at me if ya have any questions about the Black Beauty or anything else for that matter!