Plants and PH

windchill · 08-26-2006, 06:50 AM

I bought a couple of wisteria plants and put them in a one gallon bowl to ensure I dont introduce snails into my tank. I thought this would also be good for testing how fast the plants burn off nitrate in the water. The plants were isolated 8/14 and I tested for nitrates 8/21 and saw no obvious reduction. KH tested at 12. I was kind of disapointed that nitrates hadnt fallen but thought maybe a bit more time for them to adjust to their new setting was needed.

Yesterday on a whim I decided to test. First thing is, it appears the nitrates are falling some. The test is hard to read above 10ppm but depending on how I held the tube, the nitrates are between 10 and 20 ppm. I am sure it was at least 20 if not higher originally. What changed alot was the PH which is now at a definate 8.0. The water started out at 7.4 but I didnt test for PH on 8/21. The KH may have fallen a bit but is still at least 11.

The plants are not lit by artificial lights, just window sun. There is no filter/airator in this bowl either. Its been cloudy alot lately (outside) and the temps have been between 60-64 at night and 74-84 during the day.

What is causing the PH change in the water and should I expect this later in the big tank when its planted?

Blue · 08-26-2006, 07:34 AM

pH change is caused normally by the increase and decrease of oxygen and carbon dioxide. Oxygen increase=high pH, CO2 increase=low pH
pH change will happen even in planted tank.

As plants use photosynthesis in the day, pH increases as CO2 is reduced because it is being used up by the plants.
Respiration lowers the pH because oxygen is used up by the fish and plants. CO2 then increases in the process.
Fishes adapt to pH changes but not bouncing levels like pH crash as they will not readily adapt to sudden changes.

**Damon** · 08-26-2006, 03:11 PM

Well said but you forgot to mention how KH plays a role in PH flux.

KH (carbonate hardness for the most part) is the ability of water to "absorb" altering elements to keep a stable PH. While there are a few other compounds that can affect ph but not the absorbtion ability, one should not focus on those as they are not common.

windchill · 08-27-2006, 01:59 PM

Ok thanks for the answers. Well stated so I understood everything being said.

08-26-2006, 06:50 AM	#1
windchill Member Join Date: Aug 2006 Location: minnesota Posts: 33	Plants and PH I bought a couple of wisteria plants and put them in a one gallon bowl to ensure I dont introduce snails into my tank. I thought this would also be good for testing how fast the plants burn off nitrate in the water. The plants were isolated 8/14 and I tested for nitrates 8/21 and saw no obvious reduction. KH tested at 12. I was kind of disapointed that nitrates hadnt fallen but thought maybe a bit more time for them to adjust to their new setting was needed. Yesterday on a whim I decided to test. First thing is, it appears the nitrates are falling some. The test is hard to read above 10ppm but depending on how I held the tube, the nitrates are between 10 and 20 ppm. I am sure it was at least 20 if not higher originally. What changed alot was the PH which is now at a definate 8.0. The water started out at 7.4 but I didnt test for PH on 8/21. The KH may have fallen a bit but is still at least 11. The plants are not lit by artificial lights, just window sun. There is no filter/airator in this bowl either. Its been cloudy alot lately (outside) and the temps have been between 60-64 at night and 74-84 during the day. What is causing the PH change in the water and should I expect this later in the big tank when its planted?

08-26-2006, 03:11 PM	#3
Damon Aquatic Naturalist Join Date: Jan 2005 Location: Dayton, Ohio Age: 32 Posts: 14,982	Well said but you forgot to mention how KH plays a role in PH flux. KH (carbonate hardness for the most part) is the ability of water to "absorb" altering elements to keep a stable PH. While there are a few other compounds that can affect ph but not the absorbtion ability, one should not focus on those as they are not common. __________________ For in much wisdom [is] much grief: and he that increaseth knowledge increaseth sorrow. Member of the AGA (Aquatic Gardner's Association) Member of the IBC (International Betta Congress)

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08-26-2006, 07:34 AM	#2
Blue Care Bear Lover Join Date: Aug 2006 Location: Dancing with the Devil Posts: 132	pH change is caused normally by the increase and decrease of oxygen and carbon dioxide. Oxygen increase=high pH, CO2 increase=low pH pH change will happen even in planted tank. As plants use photosynthesis in the day, pH increases as CO2 is reduced because it is being used up by the plants. Respiration lowers the pH because oxygen is used up by the fish and plants. CO2 then increases in the process. Fishes adapt to pH changes but not bouncing levels like pH crash as they will not readily adapt to sudden changes.

08-27-2006, 01:59 PM	#4
windchill Member Join Date: Aug 2006 Location: minnesota Posts: 33	Ok thanks for the answers. Well stated so I understood everything being said.

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