# co2 and PH low



## dbull (Apr 15, 2011)

Does anyone have issues with low PH when using diy CO2 injection. Water tests PH 6.2, Ammonia 0, nitrite 0, nitrate .5 use API test kits. 55 gal. 11 plants. using only pea size gravel river rock. 3 pieces driftwood been in tank for 2 yrs. Fis are 8 rainbows, 6 dianios 3 black scrit tetras and 1 clown pleco 3 inch. water temp at 78. Using flourish and excel weekly. I think maybe to much ferts or co2? Running 2 small air stones with hob filter with rena xp3 cannister. If more info is needed please ask. Fish are doing fine and plants seem OK. I am just wondering about low PH. I do weekly 25% water changes. City water here and it is soft. today test was low PH but this was right from the tap.


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## jrman83 (Jul 9, 2010)

It is normal for your ph to drop when adding CO2. Are you using pressurized or DIY? You should make sure your ph rises after your CO2 cuts off. This is why it is important to make sure your water has adequate kh levels to make sure it buffers the CO2 back to the starting level. If not, the CO2 can continue to drop.


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## dbull (Apr 15, 2011)

I am using do it yourself. I was thinking with the spraybar form the cannister and 2 air stones running plus the HOB filter there would be enough water surface movement to take the CO2 out. I think I will stop CO2 for a few days and retest to see if thats the problem. i have been running the CO2 day and night. Then I will try it only during the day.Thanks DBULL


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## plantedaquastore (Jul 15, 2013)

What you need to measure is the KH level. Your KH should be between 2-4. CO2 should come on an hour before before your lights come on and off 2 hours before they go out. Do not run airstone when co2 is on.


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## dbull (Apr 15, 2011)

Todays follow up. Ph at 6.6 after 25% water change, KH at 2 GH at 3. I did remove one rock, I put in the tank a couple of weeks ago. Maybe this is the bad guy. KH and GH done with API test kit. 2 drops to change color on KH and 3 on GH. PH up from 6.1 or 6.2 to 6.4 to 6.6 in 24 hrs. Do you think I should add baking soda to raise the KH or let things alone for a little while.


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## plantedaquastore (Jul 15, 2013)

leave it alone, have you used a ph/table before?


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## dbull (Apr 15, 2011)

I will say what is a PH table? I need all the info I can get. Thank You Again.


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## plantedaquastore (Jul 15, 2013)

Simple enough. Match the kh and the ph and it will tell you your concentration of CO2 in the water. You should measure the kh and ph 1, 2 and 3 hours after the co2 has come on. This way you can see when you should turn on your lights. Plants will begin to use co2 and photosynthesize 30mins after lights are on. BTW, you want to stay in the green area.


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## ironklad (Apr 14, 2013)

That chart is very useful, thanks for posting it. So you are turning on the lights at the point where the CO2 would start to be too high, so that the photosynthesis counteracts the increased CO2 by breaking it down in the plants?

If you don't mind, I found a higher res version of that image:


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## plantedaquastore (Jul 15, 2013)

not at the too high but at higher end of the green.
good res pic.
then shut off co2 an hour or two before lights go out.


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## jrman83 (Jul 9, 2010)

I think your ph/kh looks okay and you should experience no issue. Adequate kh levels buffer the ph back to their original value before adding acids. 

Since it is a DIY system and you really can't cut it off, you have two options (providing you didn't want to remove the CO2 everyday): 1) Do nothing. Most DIY systems average about 1bps and that is not enough to hurt anything. You won't find too much info on the net about people that have gassed their fish with a single bottle DIY system. 2) Turn your airator on when your lights go out and back off before it comes on. The surface disturbance will cause the CO2 to freely avacuate the water.

Both ways you are not messing with the CO2 and just leaving it going in the tank.

Also, don't place too much stake in that table. For the most part it is useless and even more so when you are on a pressurized system.


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## dbull (Apr 15, 2011)

Thank you again. This help me to understand this a lot more. I am doing my first planted tank. As with most of us I think I was over thinking. Sometimes it is best to just do your weekly water changes and clean filters monthly. DBULL


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## plantedaquastore (Jul 15, 2013)

I scape a lot of non co2 tanks. Moderate your light, feed your plants so you do not have any limiting nutrients and do good water changes and you will be surprised how well they grow.
Without co2.


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## plantedaquastore (Jul 15, 2013)

Co2, without a constant supply of nutrients, water circulation and water changes is useless. Its like running nitrous oxide in a car; without gas, heavy duty brakes, suspension and transmission.


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## jrman83 (Jul 9, 2010)

You can say the same thing about adding a higher level light, but when you say constant supply it can be as little as a once a week dose of ferts for lower level lighting. The two main things the plant needs is light and CO2. If those are not limiting factors then the nutrients are utilized easier.


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