Hello.
I created my DIY kalk reactor with 4" PVC. Yes, it's white, but honestly, I don't care if I see into the reactor or not. It cost me ~$15 for all the parts.
Here is a site that I used.
http://jjgeisler.com/reeftank/diy_do_it ... ojects.htm
Honestly, it's very easy.
O...and I didn't...