Since I use about 2" of it per connection, I'm not too worried about it. I just wonder what the blue tubing is. The green silicon looks like hospital stuff and I use it with my O2 lines to the sponge filters. Susan -----Original Message----- From: gsas-member-bounces@thekrib.com [mailto:gsas-member-bounces@thekrib.com] On Behalf Of Erik Olson Sent: Wednesday, February 21, 2007 5:21 AM To: Greater Seattle Aquarium Society member chat Subject: Re: [GSAS-Member] CO2 blah blah On Tue, 20 Feb 2007, SUSAN WELENOFSKY wrote: > I thought silicone was better than vinyl. At least, that's what June > Olberding used, and I got her stuff for taking care of her 20-30 planted > tank room. I was talking with some of the Danes from Tropica last year (I think it was Claus Christensen back in March, but can't remember), and they said that silicone has some of the WORST permeability of tubing out there for CO2. I was surprised to hear that, but it turns out people have been saying this for years...I even have an article to that effect from 1999 on my own *!&@ website. Do a search for "permeability of silicone tubing CO2" and you'll find a thread on Aquatic Plant Central on the subject! They also mention that vinyl has much better specs. But it's all relative, of course. Yes, there's lost gas, but exactly how much? Would you notice if you had to replace the cylinder a bit more often? I've used both. Currently, I use black vinyl tubing (drip line) because it's easy to tell the difference between an air and CO2. Unless I can't find any. Then I use whatever is sitting around. I wouldn't bother ripping out existing tubing, but if given the choice of buying some fancy schmancy new silicone vs. using some old vinyl, go for the vinyl. - Erik -- Erik Olson erik at thekrib dot com _______________________________________________ GSAS-Member mailing list GSAS-Member@thekrib.com http://lists.thekrib.com/mailman/listinfo/gsas-member _______________________________________________ GSAS-Member mailing list GSAS-Member@thekrib.com http://lists.thekrib.com/mailman/listinfo/gsas-member