PH too low?

[xiaan]

We had an incident today and lost all the julies in my 25G tank  This prompted me to do a bunch of tests in the water (All ok in the 25G) in doing so we tested the 55G tank all is fine there but when I tested the PH in my 55G tank using my GHL controller it tested around 3.5 I knew it was low (it is an amazon tank with lots of driftwood and pressurized CO2) but not that low (also could be a problem with the controler as it is calibrated for High PH) I am thinking that is the reason for losing some of the fish recently (2 BN Plecos, 2 zebra loaches and 3 SAE) I am wondering how am I able to increase the PH in that tank to an acceptable level (6.0-6.5)?

[dan2x38]

Wow sorry to hear about the losses!

I had a tank's pH crash once. It was a planted tank with no injection just Seachem ferts & Excel occasionally. I determined since it had been set-up for along time & I'd not been doing deep enough gravel vacuuming. With heavy organic waste/decay it pulled the pH down. The pH was below 5 easily but I had no kit to really get a good test below that. I lost all the shrimp & snails from the tank.

I started doing deep gravel vacuuming. Than a series of water changes over several weeks. The pH started to climb back-up to just over 6. It remains around 6.6 now. A lessen learned on that one.

[fischkopp]

The pH is low, dangerous low actually. Some soft water species can tolerate this, but 3.5 becomes critical even for them.

You water is probably very soft and has not much buffer capacity, that's why you see the pH dropping. That you inject CO2 accelerates this. You will need to up the carbon hardness (KH). This can be done with baking soda.

Here is a little math tool that I found with quick-google:
http://dataguru.org/misc/aquarium/CalKH.asp?Gallons=15&KH=2&measure=0&Baking+Soda+(Teaspoons)=0.58&SKH=1&EKH=3&pHChange=0.00

[xiaan]

Thanks for the info. I think I am going to add a bag of crushed coral to the filter to raise the DKH. I will test it today (I have the test kit for my salt water stuff). What should the level be at for fresh water? I agree with Dan that it could be the increase in organics in the gravel and I need to do more water changes and gravel cleaning (I have only been doing water changes every 2 weeks). I will also add some baking soda to the tank to slowly rase the dkh.

[KLKelly]

Dataguru is the one helping me with RO water.  She built an amazing spreadsheet that calculates all the chemical amounts to reharden and buffer my water for my freshwater tanks.

If you have a kh of 0 let me know and I can email you the link to calculate how much baking soda you need.  I don't think the website one works if you have a kh of 0.  You can also type in what ph you want and it will figure it out.

[dan2x38]

In that tank that crashed I also added some crushed coral in the filter. It has been stable ever since. In my CO2 injected tanks I follow what Tom Barr does. After each water change I add some Seachem Equilibrium.

[charlie]

In that tank that crashed I also added some crushed coral in the filter. It has been stable ever since. In my CO2 injected tanks I follow what Tom Barr does. After each water change I add some Seachem Equilibrium.

Something to note Seachem Equilibrium will not impact KH, it will however impact your GH.

[xiaan]

So last night I tested the KH and it was 0 (With the salfert test kit I did not even have to put any regent in there to have it change color) I added 1/2 Teaspoon of baking powder to the tank I will add this in my tank every day and test again on Monday to see where it is. I have not got any crushed coral to put in the filter but I will pick up a small bag sometime this weekend.

[jart]

My thoughts on this:
1) Have you confirmed the pH reading?
2) If indeed your pH was <4, you will need to figure out why it went that low in the first place. Low kH is not to blame. Even if your kH was >5, it would not have protected your tank against that much of a pH swing.
3) Unless your kH is undetectable, say <1, there is no need to increase it when injecting CO2.

[KLKelly]

I'm so confused now.

[jart]

There are several myths regarding the importance of kH in a CO2 injected system.

Myth #1. The CO2 charts are useful to determine if you have "adequate" CO2.
Reality: Maybe, maybe not. Probably not.

My recent experience: growth was rather slow. Several plants severely stunted.
pH = 6.2, kH <2 (for sake of argument, kH =2). So from the chart on Chuck Gadd's site, my CO2 is 38. Which should be "good".

I took the advice of Charlie and others and purchased a drop checker. My CO2 was indeed not "good". Now my pH is 5.9 during the day. If we use the CO2 charts, my CO2 would be >75 ppm. My fish are fine.

Myth #2. In a CO2 injected tank, kH helps protect against pH swings.
Reality: This has been challenged as well.
http://www.plantedtank.net/forums/general-planted-tank-discussion/32365-low-no-kh-low-ph-without-11.html

Ex 1: Tom's aquarium has a kH = 5 and a pH of 7.4. Adding CO2 30 ppm would result in, if we trust the chart, a final pH of 6.7.
So Tom's pH changed from 7.4 to 6.7, a change of 0.7.

Ex. 2: Susan's aquarium has a kH of 1 and a pH of 6.7. Adding CO2 30 ppm would result in, if we trust the chart, a final pH of 6.0.
So Susan's pH changed from 6.7 to 6.0, a change of 0.7. No pH crash.

I just realized that Chuck gives a similar example on his web page.

Of course it can be argued that extremely low kH values (<0.1; very rare) could cause great fluctuation in pH... but some people think that this likely is not cause for concern either.

Of course if you are keeping a low light tank with no CO2 added, some plants can benefit from kH, so there may be value in adding some.

My point to the OP: we need to find out why the pH dropped so dramatically, rather than deciding on how to buffer the water.

I'm not sure as to the value of kH in a non planted tank... others should chime in. I'll be interested in hearing other folks' thoughts... debate is always a good way to learn

[fischkopp]

My point to the OP: we need to find out why the pH dropped so dramatically, rather than deciding on how to buffer the water.

That actually is a good point too.

Looking at the initial post again I would suggest to check the amount of CO2 that does in to the tank, and eventually back it off a bit. I remember people saying, that there SAE respond very quickly - in a negative way - if the CO2 is too high. I don't have any, so I can't confirm. But I have plecos and remember that they are quite drowsy if the CO2 is too high - to the point that the just fall asleep where they are and never wake up.

[xiaan]

My thoughts on this:
1) Have you confirmed the pH reading?
2) If indeed your pH was <4, you will need to figure out why it went that low in the first place. Low kH is not to blame. Even if your kH was >5, it would not have protected your tank against that much of a pH swing.
3) Unless your kH is undetectable, say <1, there is no need to increase it when injecting CO2.

1) I have not gotten an accurate PH reading both my probe and my PH test kit do not do so well below 6.0 so I know it is at least below that.
2)I think it has to do with the excess in organics in the tank I have not been doing a good job at water changes/gra the last few months (I was doing them every 2 weeks and I am bumping that up to twice a week until I get this under control)
3) my kH is at 0 so I believe the tank needs some buffering.

That actually is a good point too.

Looking at the initial post again I would suggest to check the amount of CO2 that does in to the tank, and eventually back it off a bit. I remember people saying, that there SAE respond very quickly - in a negative way - if the CO2 is too high. I don't have any, so I can't confirm. But I have plecos and remember that they are quite drowsy if the CO2 is too high - to the point that the just fall asleep where they are and never wake up.

I believe it was not a sudden drop in PH as I have not checked in a while. I have not had my CO2 on that much only 1 bubble/second and right now I have it turned off until I get my PH under control.

[dan2x38]

I use the Seachem EQ to help with the GH for the calcium/magnesium. In that tank I never worry about the KH but it is very low.

Now if I understand it right KH will not prevent the pH from raising or falling. But it possess' the property to pull the pH back to it's original level.

So the issues are like pointed out why did the pH drop? What is holding it there? Isn't staying low because the KH cannot pull it back up? Since it is off the charts...

Like I'd mentioned I had a similar issue. By raising the KH it pulls the pH back up. With better substrate vacuuming I was able to prevent the same pH drops.