I just read through this whole thread, and all I have to say is...
So how exactly are you plumbing the closed loop again?
Seriously though, I have massive, massive scratch repair envy. I might actually consider getting you to come out to my place at $100/hour to fix the scratches on my tank if they weren't all half way down on the inside. You did a stellar job.
You are going to get your limbs bitten off
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You wouldn't want to see my tank. I don't use fancy equipment and I am a noob