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**To**:**Aquatic-Plants at actwin_com****Subject**:**Re: CO2 Calculations****From**:**"S. Hieber" <shieber at yahoo_com>**- Date: Fri, 8 Mar 2002 11:17:03 -0800 (PST)
- In-Reply-To: <200203081824.g28IOfg22776 at acme_actwin.com>

Jim Miller did some calculations on the longevity of 5#s of CO2: > I spent some time researching CO2 stuff yesterday. One gram of > liquid CO2 > produces 30.5cu.in. of CO2 gas at standard temperature and pressure. > A 1/8" > diameter bubble is about .001cu.in. and at 1bps you use 86.4 cu.in. > (stp) of > gas in 24hrs. > > A fully filled 5# (2270gm) tank of LCO2 should be capable of > producing > 69235cu.in. of CO2 gas. Note that these bottles are filled by net > weight so > 5# means a 5# net increase from empty to full if properly filled. > > At 86.4cu.in. per day this should last 800 days. What's wrong with > this > picture? I haven't seen anyone claim 2+ years on a 5# bottle. > > Some ideas: no one really bubbles at 1bps, bubbles must be much > bigger, > significant leaks are pretty common, improper fills shortchanging > customers... Have you done a sensitivity analysis on your variables? One of the problems with counting bubbles instead of measuring CO2 levels is that not all bubbles are equal. So, I suspect you are right about bubble size being one thing that can account for inconsistency between the calculated and actual results. Full fills are easy to test, since it is simply the net weight. But I have been shorted a half pound or so a time or two. As for leaks. One would expect those with the purportedly leaking vinyl and silicone tubing to have substantially different refill longevity than those using the "low loss" tubing. But I submit that that those differences are very small especially compared to the kind of longevity your calculations predict. So I'm putting my money on bubble size. Are you calculating the amount of CO2 in a bubble based on a bubble at standard atmospheric pressure? My bubble counter is before the check valve, so the bubbles I count are not at room pressure but something higher. If the bubble is released low in the water column, there is more pressure, making for a more compact bubble. If you factor in these aditional variables, and we can probalby think up a few more like them, I think you'll find the rest of the CO2. Scott H. __________________________________________________ Do You Yahoo!? Try FREE Yahoo! Mail - the world's greatest free email! http://mail.yahoo.com/

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