What is acceptable PH swing

[teaklejr]

Hi. My first post on this site. I have a 54gallon planted tank with pressurized co2 injection, my lights are on for about 10 hours a day, with a aerator coming on at night. In the morning my ph will be about 6.9 and when I get home it will be 6.5-6.6 Is this ok for the ph to change this much. In the tank I have 6 ottos, 6 rasboras, 7 corys, 2 rainbows, 3 mollys, 2 flying foxs, 1 killi, 1 german blue ram, a male and female cockatoo cichlid and 1 red tail sword. Everything is going good with no problems just wanted to see if my ph sounds ok. Added the co2 injection about a month ago, definitely makes a difference on the plant growth. Any advice would be great.

 

[FroggyFox]

Others with more experience with C02 will answer too I'm sure, but I would think that if your critters seem to be OK then that pH fluxuation is going to be ok. Generally the biggest issues are if it varies in an extreme, or very quickly...I dont think .4 is too big over a stretch of time.

 

[unwritten law]

I think that there could be a bigger pH swing during acclimation, which usually doesn't take all day, so like froggy said, if the fish seem fine I wouldn't worry too much.

 

[Chris_A]

As with anything else, you just gotta "read" your tank . Let the livestock tell you if its OK. If everyone is fine and you are getting good results from the addition (the relatively new CO2) then I would say it falls under the "ain't broke, don't fix it 'til it is" catagory.

Though... One thing you could do is add a selenoid valve and timer to the CO2 line. Rather than out gassing all that CO2 while the lights are off just set the timer so it shuts off at night. If you do that though, I would remove the air at night to avoid even wider pH swings.

Chris

 

[dogdoc]

In my experience, pH swings due solely to the addition of CO2 are not stressful for the fish. I have had a pH swing of close to 1 with no adverse effects. In fact after a large water change, my tank may have a pH of 6.4 and the CO2 will bring it to around 5.5 within an hour.The fish don't even notice.

Now, a pH swing of that magnitude due to TDS changes or acid/base buffers added to the tank will kill most fish.

 

[ishar]

Let the livestock tell you if its OK. If everyone is fine and you are getting good results from the addition (the relatively new CO2) then I would say it falls under the "ain't broke, don't fix it 'til it is" catagory.

One thing you could do is add a selenoid valve and timer to the CO2 line. Rather than out gassing all that CO2 while the lights are off just set the timer so it shuts off at night. If you do that though, I would remove the air at night to avoid even wider pH swings.

Chris

In my experience, pH swings due solely to the addition of CO2 are not stressful for the fish. I have had a pH swing of close to 1 with no adverse effects. In fact after a large water change, my tank may have a pH of 6.4 and the CO2 will bring it to around 5.5 within an hour.The fish don't even notice.

Now, a pH swing of that magnitude due to TDS changes or acid/base buffers added to the tank will kill most fish.

These two basically said everything I was about to type, so I will just quote them and say I agree .