# PH Rise and I Don't Know Why



## TankAaron (Aug 8, 2014)

I didn't know where else to post a water quality question. Feel free to move anywhere else.

I use RO water. Using API pH, and High Range pH liquid test, not the strip kind, I get a pH ~6.5 when I get it from the vendor. After it's in my aquarium, the pH is ~7.5. The change isn't immediate, however I have not tested to see how fast the change happens.

I'm not actually concerned with the pH. However I'd like to try to understand why it occurs, since it seems like a big change, to me. Though I would prefer the water remain slightly acidic, I also do not want to mess with the pH. From what I keep reading, it is better to keep water quality stable, than at whatever specific target one is hoping for.

So the info is as follows:

10g aquarium (~9 - 9.5 actual gallons of water)

2x13W CFL, 6500K, 1620 lumens total, 4 hrs a day at first, now 10 hrs a day.

1mL Excel daily

1mL Flourish (I made a mistake thinking it was a daily dose. However it has only been three doses in two days. One was because I ended up doing a big water change. I just didn't plan ahead. >.> Also, the flourish has only been two days, and the water pH I have tested starting a week ago.

1 bag Flourite (I ended up spilling some, so it is probably 1 lb less than the package says.)

1 bag Flourite Black Sand

Decaying Alternanthera. There are over 120? 130? stems. They were all unhealthy. They each have had decaying leaves. I have done my best to try to clean the aquarium of them. I now hired a mysterious snail. The Alternanthera has been there since the start of the aquarium.

Now there is a lot of HC. Very little of it is decaying. Also a lot of cabomba, and one moss ball.

1mL Drs. Foster and Smith Live Nitrifying Bacteria. And I just noticed it says live... hmmm. It says to dose 5 mL for 10g at the start, and again after big water changes. However it says it cannot be overdosed, so I've also been dosing 1 mL daily. Since I got my betta, and snail, three days ago, I have been dosing 3 mL daily. I will continue to dose 3 mL daily for a week. After that, I will dose 1 mL a week, and with water changes, until the bottle is empty.

I didn't test for ammonia, nitrite, or nitrate until a few days after I set up the aquarium. I then tested for ammonia, and pH. I noticed there was some ammonia, so I realized the nitrogen cycle had started. I skipped a couple of days then tested pH, ammonia, and nitrite. There was very low nitrite, this time. I skipped a few days, then I retested. Now the ammonia was zero, nitrite was zero, nitrate was ~5 ppm. After three days of getting zero ammonia, zero nitrite, and ~5 ppm nitrate, I got a betta, and a mystery snail.

Ammonia: It was zero for three days in a row. After I got my betta, and snail, it has risen to ~0.25 ppm. What's weird is that it remained about the same even after a water change.

Nitrite: constantly zero.

Nitrate: fluctuates ~5 ppm. I added more plants, cabomba, so I figure it may go lower.

I use 1 AquaClear 20, filled only with Matrix. The intake has a sponge on it.

Temp: ~ 77 - 78 F (~25C).

I neither do anything else to the aquarium, nor dose anything else. I recently added seven small pebbles to weigh down some HC. However I added the pebbles yesterday, and I have been testing the pH since last week with the mentioned results. I have tested the pH about four times during the week, or so, when I set up the aquarium, each time with the same results. I have tested the RO water twice.

At first I figured it was the substrate, however Seachem states that neither Flourite, nor Flourite Black Sand will affect the pH.

Again, I am not concerned with the pH. It is not fluctuating in the aquarium. Obviously it rises from the ~6.5 to ~7.5 pH once in the aquarium, however it seems to remain stable once it rises to ~7.5 pH.

I am not wanting to change the pH, nor enhance it artificially. I would prefer it remains constant at a higher level than I wanted, than to artificially alter it. I only would like to understand why it is happening.


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## pandragon (Jul 10, 2014)

Ph changes drastically with ro water since ro water has nothing else in it to keep ph stable. Tap water has naturally (and artificially if your tap is city water) minerals like calcium carbonate that help maintain a stable ph when the water comes in contact with any liquid or gas that acts like an acid. Co2, for instance, lowers ph while it is dissolved in the water but once the plants use the co2 or the water gets stirred up by say a bubbler, the co2 trades places with other gasses and the ph rises. You might have lower ph at night when the plants are not using the co2 for growth. If you decide to inject co2 you will have to add crushed coral, lime, or another form of calcium to keep the ph from dropping too low, but you could maintain a constant ph by adding co2. But injected co2 is better left explained by the experts here.


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## TankAaron (Aug 8, 2014)

I understand that. However that doesn't explain why my pH is rising to ~7.5 in the aquarium. If it was due CO2 from Excel, my pH would go lower than ~6.5, the level my RO water starts at, not higher.


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## pandragon (Jul 10, 2014)

Excel isn't co2, its some other things some plants can use the carbon from. I am no chemist and have never use it, but itsn't the same as co2 dissolved from the air or injected from high pressure tanks. Pure water is corrosive and unstable and binds with lots of stuff in the air and tank to stabilize its ph. Ammonia can change ph as well given enough of it in the water, not sure what .25ppm would do. It is really hard to say exactly what made the water go to 7.5 rather than 7 (neutral) other than that water is more stable at 7.5 with whatever is in the environment of your water. Without a constant acid source water likes to stay over 7 in my experience.


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