DIY CO2 'bell'

Blinky

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Jun 22, 2004
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I'd like to ask your opinions on using a CO2 'bell' - I've been using a 4" bubble wall with my DIY system, but have learned that it can create back pressure on the bottles over time and this can cause a bottle to explode (thanks for the heads up, Len, my living room floor appreciates it!). I don't want my house to be sticky and smell like a brewery, so I'm looking for a better method of getting the CO2 into the water.
Today I installed a 'bell' - upside down plastic dome, airline connects to the top and feeds in the CO2. There is enough gas coming from the bottles that the bell fills up in about an hour. The result is that the bell is constantly full, and about every 10 minutes a huge bubble pops out the bottom and rises to the surface.
I'm wondering, will the CO2 diffuse into the water properly if this is happening? I haven't seen a drop in pH since this morning, leading me to believe that this isn't any more efficient than the bubble wall was, but at least some CO2 must be getting into the water. I'm happy to leave the system as-is if it's going to work, since it solves the back pressure problem - at least until I get the energy and materials together to make an in-line diffuser for my cannister filter.
Thoughts?
 
I tried a DIY bell and had the same problem you have. I ordered one of these on Saturday night and am curious to see how it fares.

www.aquacave.com/co2_diffuser.htm

I've got three 2 liter bottles running on my DIY and have a check valve for each bottle to prevent them from interfering with each other. I replace one bottle every week and rotate the others. It's a pita but will have to do for now unless I can convince the wife and kids that they need pressurized CO2 for Christmas ;)
 
I'd love to hear about your experiences with that diffuser when you get it.

I'm still using the bell (it's been a busy week, no time to build a DIY diffuser) and it's still constantly full and letting a huge bubble out every ten minutes or so, but some CO2 must be getting into the water since the pH is 7.0 and pre-CO2 injection it was 7.5-7.6. The plants are growing like weeds (well, technically they are weeds, lol) so I'm leaving well enough alone for the moment.
 
Well the diffuser finally made it to my house today so I've finally got it hooked up tonight. It's been connected for about an hour and I can see the bubble counter working but so far no CO2 is coming out. The ceramic stone seems to be really fine so maybe it will take a while for the gas to work through it.
 
Ok sometime between last night and when I got home from work this evening, the diffuser started producing the most tiniest of bubbles. I'm quite impressed with it. I have it sitting as close to the bottom of my tank as possible and about 30% of the bubbles dissolve before hitting the surface. The rest are blown away with my filter outlet. My Ph was at ~6.6 and kH at 4.5. Not bad for DIY on a 75g. I'm still going for compressed though. The DIY is a hassle and probably more expensive in the long run.

I'll see about getting a photo up if ya want to see it in action.
 
Sure, that would be great! It sounds like it's working well for you.
I've given up on the bell, it was driving me nuts, glurping every ten minutes. I fed the airline into my canister's intake, and while I haven't noticed any appreciable difference in the amount of CO2 in the water, my living room is a lot quieter!
 
I'm using DIY CO2 and it's running fine. I still need to get a photo of it running but time has been scarce this week. Next week I'm going compressed though :D
 
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