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Discussion Starter #1
Hi guys, went through a lot of discussion with Tom Barr on this topic offlist and he always mention that it only takes about an hour or so to return the CO2 levels back to the optimal range of 20-30ppm even after say 50-70% water change. I have tried different types of reactors (internals/externals), changing of flow patterns in the tank but have yet to get that type of fast response that he seems to be getting. Currently, my 20 gallon tank with a powerhead powered internal reactor takes about 3-5 hours to return the CO2 back to optimal range after a 50% water change. I would like to hear your views and personal experiences on this. Thanks in advance.
 

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Why do you need it to come back so quick? Maybe he is using the PH controllers that may do it faster. Will anything bad happen if things dont come back so quickly?
 

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Discussion Starter #3
> With high GH and KH and pH tap water, a 40-60% water change is taking my
> CO2 down to around 5 ppm (or whatever normal ppm is without supplement).
> It takes about 1-2 days (sometimes more) for the pH to recover to the
> 7.1-7.3 range I try to keep it in.

A decent CO2 system would keep the pH in a good range within 1 hour or so.
If it takes days to hit a good range, how is it that the system is able to
keep up with the plant's uptake depletion rates?

CO2 is the biggest issue for you. And it will cause the most grief if it's
not well set up and responsive.

I know that everyone's circumstances are
> different (tap water GH, KH, pH, and w/g, fish and plant load and needs,
> etc.) but I suspect that this is probably where my tank differs from
> most of yours and is the area I should look into first. After you do a
> 50% water change, how high does your pH go and how long does it take
> your tank to come back to the desired pH?

About 1 hour or so.
pH, KH, GH of the tap etc really doesn't matter. It's all about the
CO2/uptake/mixing rate/flow rate etc.

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Taken off APD and the response was from Tom Barr
Shane, the reason is as stated above. I did wrote to Tom offlist and he did confirm that it should take an hour or so at most for whatever tank size. How fast does your CO2 level return to optimal range say after a large water change? 8)
 

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I think KH may play at part.
If one has low KH tapwater, a waterchange will reduce the KH and accelerate the pH reduction process.

So I think something like below will improve the response time.

Change water, increase CO2 bps, CO2 level back to normal, bring up KH to normal levels, reduce CO2 bps to normal.
 

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It takes my tank 3 hours to go abck t 25ppm, then at the end of the day i am at 35ppm. I jusy blacked out my tank(Well my dad did while i was away) and he has left my co2 off entirely for the beginning part of the afternoon. I just checked co2 and turned it on at 1 now its 2 and the co2 is at 20ppm. But i do not have a ph controller. All i do is after the water change let out a hard burst of co2 to get it back up then settle it down to a beat every 3 seconds. With a reactor 1000 on a 50gallon getting the co2 up fast is pretty easy. Every bit is dissolved very fast. I never even see the bubbles in the reactor the dissolve almost before they can show themselves. I also test with a lamotte co2 test kit instead of the PH and KH thing. The test kit is just easier are pretty cheap $19.95.
 

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Discussion Starter #6
Aquoi, KH does not play a part in it at all. Its all about mixing rate, uptake rate and flow rate in the tank/reactor. :? What I wanted to know is does folks have reactors that gave such fast response time?

Shane, without cranking the bubble rate up, are you able to get a fast response time as well? Where does you return line from the reactor 1000 go inside the tank? Tom mention to me that faster flow rate equal to more mixing and hence better response time. As long as the bubbles are not blow out from the bottom of the reactor, you are fine. The way the reactor line is placed in the tank also has an impact. It is best placed along the bottom back edge with a spraybar pointing towards the front of the tank.
 

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My modded reactor is so efficient that I don't see any stray bubbles in it and out of the outlet, even when I jack it up to 10bps (just to test)...
I just changed the water on Sat so I'll test it a few days later.
 

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The reactor is inline with my fluval 304 at full blast. I think its 300 gallons per hour or something like that. The intake for the filter is on the back right corner and the spray bar is on the left side pane of glass spraying across the tank. I always crank the co2 up so next time i do a water change i'll not and see what happens. I am guessing it will take way more than an hour.
 
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