CO2/ph/Kh

[Husmut]

I read in another thread that, depending on what is present in your aquarium, (ie: natural buffers like rocks that leak calcium, which I have) the readings you get for ph and Kh may not give a true indication of CO2 levels. It was suggested that you remove a small amount of water and leave it out till the excess CO2 leaves the water and take a ph reading to note the difference between it and the tank.
My readings are Kh:4.5-5. Tank water ph is 7.5, removed water ph is 9.0!
What does this tell me about CO2 levels in my tank?

 

[greenmaji]

http://www.bestfish.com/oldtank.html check out this link and make sure that is not your problem.. you might not have a problem by the way..

Did you test the KH of the removed water?

 

[hashbaz]

Your CO2 causes a significant (1.5) drop in PH. I'm no expert, but I would guess you have either enough or too much CO2.

When the CO2 charts are invalid, observation is the best measuring tool. How are your plants and fish doing?

Do you know why your natural PH (no CO2) is so high? This seems very odd.

 

[Husmut]

I am pretty sure the ph is this high because of the smattering of 9mm white river stones (a product of india if this is relavent) I put in my tank a few months back. My tap water sits at 6.8 ph so this is the only thing I can think that has caused it. Fish and plants are fine. Ill do the test again cause I did not measure kh on the removed water.

 

[wabyrd]

Your CO2 causes a significant (1.5) drop in PH.

Not that significant. It's barely noticeable. Besides, not all of the CO2 will leave the water. Take sterile distilled water's pH in a CO2 free environment and you get 7.0, but in room air CO2 will go into the water slightly lowering the pH. No to mention the fact that biological activity is still taking place in the water removed from the tank which also can change the pH.

 

[greenmaji]

Just as observation... the KH seems too low for the PH thats all... are you using any salts or buffers?

 

[malkore]

got a phosphate test kit? high natural or artifical phosphates (from a pH up product) will screw up the pH/Kh relationship for CO2. pH down products contain acids which give false CO2 results too.

There are certain chemicals your water company may be adding that give a much higher pH compared to Kh. I'd like to see what your tap pH and Kh is like when it's rested for 24 hours.

I can't find the post that explained exactly what was going on, but you could call your water company and ask them for a report, or if they have an engineer type person that can tell you how they treat it, and why you might get high alkalinity but low pH readings.

 

[greenmaji]

I think I remember you saying that you buffered your water with CC or something in one of your first posts.. If so your KH has come down quite a bit.. but malkore is right it sounds like something might be in your tapwater if your not adding a ph up product..

 

[hashbaz]

Your CO2 causes a significant (1.5) drop in PH.

Not that significant. It's barely noticeable.

I'm sorry if I sound argumentative, but why do you say this?

When I look at the CO2 charts, a PH drop of just 1.0 signifies that the CO2 has increased by 10 times.

 

[greenmaji]

I think he is trying to say that the PH drop is barely noticeable to your inhabitants not that it doesnt have an effect on the CO2 level; because it does indicate that you are getting more CO2 into the water..

 

[Husmut]

Nothing like this has ever happened to previous setups, and this one was going exactly the same till I did two things; Added CO2 and added these stones. Im checking out the stones. Just grabed a few and put em in a glass of tapwater overnight. If they do turn out to be the culprit, is it bad to have this "natural" buffer in the tank when adding CO2?

 

[greenmaji]

It would be PO4 sources that you should be looking out for.. from what I understand..

 

[Husmut]

Phosphate? Are you thinking this is from the stones? FYI, I tested the water with the stones in it this morning, and the ph was up from 6.8 to 7.4. (after about 9 hrs) How does PO4 fit into this?

 

[RoLeX]

I read in another thread that, depending on what is present in your aquarium, (ie: natural buffers like rocks that leak calcium, which I have) the readings you get for ph and Kh may not give a true indication of CO2 levels. It was suggested that you remove a small amount of water and leave it out till the excess CO2 leaves the water and take a ph reading to note the difference between it and the tank.

Can i please have a link to this thread as ive done a search and nothing came up TY in advance

 

[greenmaji]

sorry I dont know were that tread is but I missed a question from before..
PO4 sorces.. rotting fish food mostly.. overfeeding...
and I think I was off my rocker when I made that comment.. I dont see how it fits into this right now.. 8O

KH leaching from your rocks will throw off your readings.. and raise your ph.. CO2 will make these same stones relise even more KH.. it would be best to leave them out of the tank.. unless you need the harder water for african cichlids or somthing.. but thats rare..