Some questions of pressurized CO2 injection

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falcon

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Dec 16, 2003
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Ok, I have a 120g setup with pressurized co2 injection. I have the whole setup, controller, solenoid. My question is, I keep my ph at around 6.7-6.8 and my aged tap water is around 8pH. When I do weekly w/c of around 50%, I will have to do a catch up on the pH differential. What is better, having the co2 go into the system really fast at say about 150 bubbles/sec or going more slowly at say 60bbl/sec. I have it going at a faster rate and it takes me about 4 hours to match he pH at w/c. I would imagine with the lower bubble count, the match would take upwards of 8 hours. I am debating as to what is less stressful on fish. Also, after I do a w/c, I get a differential of 0.4 pH or close to it.

Is anyone doing something different to lower the pH differential gap at w/c?

Thanks.

falcon
 
What you are doing is pretty stressful and time consuming and could harm your fish as for a span of 4 hrs, you lower your pH by .8! I do something different. I have pH minus solution and every time I need to replace 25% of the tank water, I fill a large backet of 70l with fresh water and treat it with the declorinator and use the portion of pH minus to the tank level reading.
That's how you gaurantee the correct pH with no harm done to your fishies!!

I hve been practicing this for a year now and have a 55gal tank, so my 25% is nearly 70l.
 
Do you age all of your water for changes or just the water you tested? If you already age it all anyway, perhaps you could inject enough CO2 to get the pH right before adding it to your tank.
 
Cgrabe, yes, I age all my water before w/c. I have two barrels, one 65g and one 55g. 55g will be used for my 65g tank that I am setting up with pressurized co2 as well.

That's an idea, ad co2 in the holding tank. The only thing, I would another co2 gas bottle, reactor, and what have you - not cheap. Also, when I do w/c, I pump the water from the storage into the tank. The water cascades into to tank for about 30min. This will remove some of the effect of co2. Any ideas?

Cybermate, I know that is a pH differential at w/c. But I'm thinking maybe the effect is not that large as everything happens fairly quickly. I mean you go from a stable 6.7 to 7.1 or so after w/c but then fairly quickly you go back down to 6.7. Maybe the change is quick enough and the effect won't be too stressful? don't know...I would understand if I had a pH of say, 7.4 for few months and then within few hours I would lower it to 6.7 - that's lethal. Any thoughts? I have heard a lot of bad things about using chemicals to lower pH (pH minus and the like) - not sure what else it affect. But I mean, if that's the only solution and it's better that what I'm doing now, could give it a try.

Any more ideas/suggestion guys?

falcon
 
I haven't used CO2 myself, but would it be possible to add a second line to your current setup between the regulator and solenoid with a simple ball valve to run to the aging water?

As far as the water cascading, is there any way you can reduce the surface agitation? I don't know how exactly you pump it in, but I would think placing the outlet tubing below the surface of the water would go a long way.
 
Yeah you wouldn't need another setup. just get a T fitting and connect it directly to your regulator output, then get another needle valve and stick it on there

voila! two needle valves, two outputs.
 
A slight complication. For the 120g setup, the storage tank is about 30' away. Second, I have one of those regulator/solenoids/bble counters in one setup and it is connected to a controller. For the line, you cannot use airline tubing as the co2 loss would be tremendous and I'm not sure how the distance affects co2 distribution. I would think you also need a reactor and a proper means of moving the co2 within the water column to properly dissolve it. Also, the additon of a solenoid in the setup complicates things even more. The 120g gallond will disctate when co2 is dispensed. Am I right?

falcon
 
Have you measured the pH after a 50% water change to see how much it's risen?
I changed off 60 - 70% water in two 55s yesterday. My water is 7.4 coming out of the tap and 6.4 - 6 in the tank. I let the water come down on it's own after the change and have never had a problem with stressing fish. My fish love the water change and actually gain color and become more active.
Test your tank water after the change. I'm guessing that it's not going to drop as much as you might think.
I would say turning the CO2 up and down will cause more problems than the differential in pH between tap and tank.


Len
 
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Len, the pH rises 0.3-0.4 pH after a w/c. My question was since I do pressurized co2, I can drop back those 0.3-.4 points in 3-4 hours or go slower and do it in 8 hours or more, is it better to drop the pH down again slowly or go faster? Right now, my bubble rate is probably around 200bbs/min. With the controller setup, I don't really have to watch the bubble rate.

Thanks.

falcon
 
I am totally lost by this conversation. I never have more than two bubbles a second of C02, sometimes 1 bubble every 2 seconds. You need to know what your KH is, and what your pH is before adding C02. Then use your C02 to lower your pH. Read Chuck Gadds C02 chart and info. The KH is the only thing you need to ajust to act as a buffer for the C02. I would add the C02 directly to the tank, not to a storage tank. If you have a sump or a wet/dry filter, the C02 will be burned off as the C02 enriched water splashes into the tank. Get you KH to 3 to 8 degrees and then look at the C02 chart to see what your C02 level should be. Get an internal or external C02 reactor that mixes the gas with water without losing any of the gas.

A water change may temporarily affect the pH, but the C02 particularly with a controller will bring the pH back down, but not all at once....gradually. Some pH swing is normal and fish can usually tolerate it without any problem.

Your KH may go up and down somewhat when you do waer changes, you just need to test your KH more often and ajust the controller based on the KH and Chucks chart.
 
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