PH Question

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cbsmith

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Sep 8, 2003
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I have a planted tank that is stocked with 2 angels, some tetras, a gourami, and some danios. The tank is being injected with CO2 from a Hagen DIY CO2 system. I am also dosing Flourish products for the plants.

The PH has been consistly at 6.1-6.2 which seems really low to me. I know angels and tetras like a lower ph, but I figured around 6.6-6.8. The fish seem to be doing fine but I am wondering if I should raise the ph and if so how should I do it? I tested the ph of my tap water and it is 6.6.

Thanks.
 
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How large is the tank? From what I've read, the Hagen systems don't produce much CO2, so I'm guessing it's either a small tank or your KH is very low.
What's the KH? If it's below 3, ~50ppm, it's a good idea to buffer the water to avoid a pH crash. Baking soda works well, 1/4tsp per 10g is what I use in my tanks (my water is quite soft, 20ppm Ca, KH 50ppm). If you haven't got a KH test kit, it's a good idea to get one so you can keep tabs on the level of CO2 in the tank (there's a relationship between KH & pH, you can use the two measurements to determine ppm of CO2).
 
The tank is a 25g high. I think our water is soft so the co2 could be lowering the ph. I will get a kh test kit on Monday and see what it is.

Thanks for the info about the baking soda.
 
Thanks for the help Blinky. My KH was less than 10ppm. I have started to raise it with baking soda and the KH is around 50ppm now nad hte ph has come up to 6.3. I am going to keep raising it slowly over the next few days to bring the ph n the tank up to about 6.8 or so.
 
Once you raise the kh it won't stay there, you need to continually buffer your water with limestone, coral etc. I'd say if your not getting any ph swings leave the ph as it is. Also they're must be alot of Co2 being injected into your water or your ph test kit is bunk. Because unless your an :joe:, a kh at 50ppm your ph should be 7, 7.2 range. So if it is at 6.3 you are getting a ton of Co2. You need to buffer your water or you are going to lose all of your kh, and your ph is going to crash. I'm guesssing this tank is fairly small, or the co2 system is working extremely well. Add a couple of teaspoons of crushed coral to your filter. Untill you get the desired ph.
 
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I agree that adding something like crushed coral or a cuttlebone (available in the bird section of your local pet shop) is a good idea, but from what I've read it tends to work very slowly, so I'd use baking soda as well.
I add baking soda at each water change to keep the KH in my tanks above 50ppm (it's ~70ppm out of the tap, so it's more preventative than anything).
 
Right now the KH is at 50ppm and hte ph is at 6.6. The ph of my tap water is 6.6 and the kh is only about 30ppm, so it is really soft.

For CO2 I only have the Hagen DIY co2 system and it is on a 25g tank so I don't think that the co2 could be that high, but maybe it is. Does anyone have a link to the chart that will tell me my co2 based on kh and ph?

I am going to start buffering my tap water up to about 70-80ppm when I do awater changes with baking soda. Hopefully that will help keep the kh high and ph constant at around 6.8 once I get the tank to that level.
 
Here is the Link to measure th eco2 in the Tank.

you could down load a cal for your desktop if you wanted from the same site..

HTH
 
I'm sure you already checked, but your co2 is in the range of 19ppm on the chart. Not really that high by most standards. I would get the Kh at or above 3 dkh (54 ppm) and keep it there. You will have to add something to your change water each time. baking soda is the fastest dissolving carbonate form easily available. if you put crushed coral in your filter, it will counteract consumption very well.
Dave
 
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