[ChocolateChipStar]

During the initial cycle, my pH has been at a stable 8.1 (I know it needed to come up, but I didn't want to mess with anything during the cycle.)

After my water change, the pH is as of yesterday now down to 7.9. Is this normal? Alk. is fine, so do I need a more accurate test? (I was thinking that I understood that they kind of went hand in hand.)

I've read about adding baking soda to raise pH, but is this really an okay thing to do? I don't want to add chemicals, so I'm not sure about the baking soda.

[pogodzib]

Here's a couple quotes from some of my previous responses to low pH levels. Hopefully, they will help you learn a little about pH in aquariums.

Assuming that your test kits are all accurate, my guess would still be that it is from excess CO2 if your not adding any chemicals besides kalk, although getting more fresh air into your skimmer should have helped. Have you read this article? Chemistry and the Aquarium IMO, it is the best article on the web dealing with pH in aquariums.

Take a bucket of water out of your aquarium and place it outside for a few hours with a powerhead or air pump circulation the water and rippling the surface. This will drive off most of the CO2 in the water. After you do that for a while, retest the pH of the bucket of water and see what you get. If the pH in the bucket is higher, you still have excess CO2 in your tank's water.

You should be using the unscented baking soda to raise your alkalinity levels if your levels are low. Doing this will help buffer/raise your pH. Don't just keep adding ANY chemicals to raise your pH. If you alkalinity levels are in the optimum range and your pH is still low, more than likely you are either adding pH lowering chemicals into your tank or your tank has a high carbon dioxide level (very common) in it (usually because your house has high levels in the air). If you add baking soda, washing soda, baked baking soda, or any other pH buffer/raising chemical without knowing where your alkalinity,calcium, and magnesium levels are you are asking for trouble.

BTW - I've had tanks remain in the 7.7-8.0 range and everything thrived. In fact, during winter months it was common for my pH to drop to around 7.65 in the morning. Just remember that stability is just as important as optimum readings.

Baking soda, and most other pH adjusting additives, help to raise the pH by raising the alkalinity. I NEVER add any chemicals aimed specifically at adjusting the pH. 90%+ of the time if pH is low, some other water parameter is off, something is being added to the tank that is lowering the pH, or their is a high carbon dioxide level in the tank.

BTW - pH may fluctuate by as much as 0.25 throughout the day. Generally, it will be the lowest right before the lights come on and highest when the lights shut off.

[lynnvangsnes]

Is this a brand new setup? If so, what kind of substrate do you have? How much if any LR are you using and where did you get it? A new tank shouldn't have ph probs so early in the cycle unless there is a problem with something that has been put in the tank.

[ChocolateChipStar]

Thanks for the info, Pog. When I tried to search pH on the link there were too many threads for it to show. I'm glad to hear that I can still be okay, even if the pH is a bit lower than perfection. I was just concerned about the sudden drop right after the first water change.

Lynn, yes, this is a new set up, and the pH dropped from 8.1 to 7.9 the day after I did my first water change. I'll just keep an eye on it and see if it goes up a bit or if that's just where it wants to stay.