# [Wet Thumb Forum]-should I lower the ph or higher the kh?



## aviel (Sep 12, 2004)

Hi,

I have CO2 = 35 ppm, that is ph=6.6 and kh=4.
I want to raise to say 45 ppm.
so it's either that I lower the ph or increase the kh and I don't know which way to go.

If I lower th ph then maybe it's not good for the good bacteria and I heard fungi stuff.

If I take a higher kh - then I add drinking soda - is that a problem? too much sodium bicarbonate?

Aviel.


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## aviel (Sep 12, 2004)

Hi,

I have CO2 = 35 ppm, that is ph=6.6 and kh=4.
I want to raise to say 45 ppm.
so it's either that I lower the ph or increase the kh and I don't know which way to go.

If I lower th ph then maybe it's not good for the good bacteria and I heard fungi stuff.

If I take a higher kh - then I add drinking soda - is that a problem? too much sodium bicarbonate?

Aviel.


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## imported_aspen (Feb 20, 2003)

do you have fish in there? ime they won't last long if you go that high with the co2.

rick


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## aquabillpers (Apr 13, 2006)

Hello,

Changing the KH or artificially lowering the pH will have no affect on the amount of dissolved CO2 in the water. 

CO2 drives the pH, not the other way.

In your situation, the only way to increase the amount of dissolved CO2 is to pump more in. 

But, it is unlikely that the plants will make use of the extra CO2 anyway. I think that 30 - 35 ppm is the upper useful limit. but perhaps someone more knowledgeable than I can confirm
that.

Bill


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## trenac (Jul 16, 2004)

Why would you want to raise the C02 up to 45ppm? A good range to keep is 20-30ppm anything over that is on the high side and could harm your fish. Your KH of 4 is good for injecting C02. However if you want to raise it you can add bakeing soda which will also raise your PH. Is your PH of 6.6 with lights on or off?


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## aviel (Sep 12, 2004)

Oooops forgot to mention,

I am using a PH controller so if I lower the PH or higher the KH - it pumps more CO2... of course I can't change the CO2 just by playing with KH/PH...

As for the fish - I am monitoring them, carefuly, they are not coming up to the surface to breath, or am I overlooking something?

Now for the original question - what would be best for the growth of my plants - to raise the KH or lower the PH?

Aviel.


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## imported_aspen (Feb 20, 2003)

>>'As for the fish - I am monitoring them, carefuly, they are not coming up to the surface to breath, or am I overlooking something?'

co2 stress will set in over 30 ppm. a good way to monitor this is to put some shrimp in there. they are a first sign your co2 is going too high- they will keel over before the fish die.

take a sample of you water, aerate it and check the ph and kh after aeration. this is a better check to see how much ph you have in there.

are your plants pearling and growing like mad?

rick


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## aviel (Sep 12, 2004)

Wouldn't say pearling like mad!
Pearling yes - some of them are over pearling but some are not pearling - for example the stunted eusteralis is barely pearling.

Yes I do have shrimps and I see them - they are fine and I think it does indicate that I can go higher.

Aviel.


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## trenac (Jul 16, 2004)

What is best for the growth? Raising C02 alone is not going to help; you need a balance in nutrients and lighting also. What is the readings on your N03 & P04? What type and how much lighting do you have? What is your fert regemin?


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## aviel (Sep 12, 2004)

Tank has 2.9 W/G, no3=13 ppm, po4 = 1.0, 0.06 ppm Fe is added daily, GH=8, PH=6.5, KH=4, Ammonia=Nitrite=0. I add K2SO4 only if pealing is low or NO3 doesn't drop. I also add CSM+B for micros. Tank has 4 Inch quartz over 1 inch JBL substrate and middle layer of laterite. Temprature runs from 82 to 85. UV light is on.

Aviel.


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## imported_aspen (Feb 20, 2003)

imo if you have 30 ppm of co2 your tank should be going great guns. i would take out a sample of tank water and aerate it and fully test it, to verify those results. you shouldn't have any stunted plants with what you got going there, and maybe one of your variables is not what you think it is. no offense, but i just wonder why you aren't chopping 1/3 of your tank weekly with those numbers, given that they are all correct.

rick


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## aviel (Sep 12, 2004)

OK did some measurements:

tap water kh=5 ph=7.54 CO2 = 5ppm
aerataed aquarium water kh=3 ph=8.4 CO2 = 0.45 ppm.
aquarium water kh=4 ph=6.5 CO2 = 44 ppm

So the sample that I took out of the aquarium and aerated showed PH=8.4 which I believe indicates that without the CO2 - really I don't have any other acidity contributor. So it's pure 44 ppm that I have in that tank... 

But back to my original question - when increasing CO2 - what is more healthy - should I go for a lower PH with the same KH or should I increase artificially the KH such as to avoid PH going below 6.5.

Aviel.


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## trenac (Jul 16, 2004)

If it was me I would increase my KH.


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